JP5841558B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire including at least one rib continuously extending in a tire circumferential direction in a tread portion.

  Conventionally, the tread portion has a tread pattern that includes a plurality of main grooves extending continuously in the tire circumferential direction and a plurality of ribs divided into the main grooves and extending continuously in the tire circumferential direction. Tires have been proposed (see, for example, Patent Document 1 below). This type of tire has excellent drainage and extremely high rigidity in the tread portion, and in particular, excellent turning performance on wet road surfaces.

  A plurality of lug grooves that are inclined with respect to the tire circumferential direction and extend from a rib edge on one side of the rib and that have a terminal end in the rib are formed on the rib of the tire of Patent Document 1 below. ing. Such lug grooves improve traction performance on wet road surfaces. The rib is provided with a plurality of sipes between the lug grooves adjacent to each other in the tire circumferential direction. Such a sipe reduces the rigidity of the rib and suppresses uneven wear at the rib edge.

JP-A-8-91023

  However, in the conventional pneumatic tire, the plurality of sipes between the lug grooves generally reduce the rigidity of the ribs. For this reason, there exists a possibility that the turning performance on a wet road surface may fall.

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a pneumatic tire capable of suppressing uneven wear of rib edges connected to lug grooves while maintaining turning performance on a wet road surface. It is said.

The present invention provides a pneumatic tire including at least one rib continuously extending in a tire circumferential direction on a tread portion, wherein the at least one rib extends from a rib edge on one side in the tire axial direction of the rib. And a plurality of first lug grooves having ends in the ribs, a plurality of second lug grooves extending from a rib edge on the other side in the tire axial direction of the ribs and having ends in the ribs, and the first lugs A plurality of sipes not communicating with the groove and the second lug groove are provided, the first lug groove and the second lug groove are inclined in the same direction with respect to the tire circumferential direction, and the first lug groove and The second lug groove is disposed at a position where 80% or more of the tire circumferential direction component of the first lug groove faces the second lug groove in the tire axial direction, and the sipe includes the first lug groove and the second lug groove The other side opposite to the second lug groove Inclined, and characterized in that it comprises a first sipe which is provided between the first lug groove and the second lug grooves facing in the axial direction of the tire.

  In the pneumatic tire according to the present invention, it is preferable that the first sipe is arranged on a straight line connecting the first lug groove and the second lug groove facing in the tire axial direction.

  In the pneumatic tire according to the present invention, the first sipe is arranged on a straight line connecting the terminal end of the first lug groove and the terminal end of the second lug groove facing in the tire axial direction. Is desirable.

  In the pneumatic tire according to the present invention, the sipe includes a second sipe that is disposed between the first sipe adjacent in the tire circumferential direction and has a first component inclined in the same direction as the first sipe. It is desirable to include.

  In the pneumatic tire according to the present invention, the second sipe includes a circumferential component extending in the tire circumferential direction on the inner side in the tire axial direction of the first component, and an outer side in the tire axial direction on the outer side in the tire axial direction of the first component. It is desirable to have an axial component that extends.

  In the pneumatic tire according to the present invention, the tread portion includes at least three main grooves extending continuously in the tire circumferential direction, and the rib is divided between the main grooves and one side of the tire equator. Or it is desirable that it is a middle rib arranged on the other side.

  In the pneumatic tire according to the present invention, it is preferable that the first lug groove and the second lug groove are inclined at an angle of 45 to 70 ° with respect to a tire circumferential direction.

  In the pneumatic tire according to the present invention, a ratio (L1 / W1) between a length L1 in the longitudinal direction of the first lug groove and a width W1 in the tire axial direction of the rib, and the second lug groove The ratio (L2 / W1) between the length L2 in the longitudinal direction and the width W1 of the rib is preferably in the range of 0.3 to 0.5.

  In the pneumatic tire according to the present invention, it is preferable that the first lug groove and the second lug groove have a groove depth that gradually decreases toward the end side.

  In the pneumatic tire according to the present invention, the ratio (D2 / D1) of the rib edge side depth D1 and the terminal side depth D2 of the first lug groove and the second lug groove is 0.4. It is desirable to be in the range of ~ 0.6.

  In the pneumatic tire according to the present invention, the shortest distance L3 from the terminal end of the first lug groove or the terminal end of the second lug groove to the first sipe is in a range of 1.0 to 5.0 mm. Is desirable.

  In the pneumatic tire according to the present invention, it is preferable that the rib includes a chamfered portion in which an acute angle portion formed by the first lug groove or the second lug groove and each rib edge is chamfered.

  The pneumatic tire according to the present invention includes at least one rib, a plurality of first lug grooves extending from a rib edge on one side in the tire axial direction of the rib and having an end in the rib, and the other in the tire axial direction of the rib. A plurality of second lug grooves extending from the side rib edge and terminating in the rib, and a plurality of sipes not communicating with the first lug groove and the second lug groove are provided. The first lug groove and the second lug groove are inclined in the same direction with respect to the tire circumferential direction, and the first lug groove and the second lug groove are arranged at positions facing each other in the tire axial direction. ing. The sipe is provided between the first lug groove and the second lug groove that are inclined to the other side opposite to the first lug groove and the second lug groove and face each other in the tire axial direction. The first sipes are included.

  In the pneumatic tire of the present invention, drainage is improved by draining from one side and the other side of the rib on the wet road surface by the first lug groove and the second lug groove. Therefore, on the wet road surface, the contact surface where the tread portion and the road surface are in contact with each other can be increased, and the traction performance on the wet road surface is improved.

  In the pneumatic tire of the present invention, the rigidity of the rib is reduced by the first sipe in the vicinity of the first lug groove and the second lug groove facing each other in the tire axial direction. For this reason, the rib edge connected to the first lug groove and the second lug groove can be more easily deformed, and uneven wear of the rib edge can be suppressed. Further, the first sipe does not communicate with the first lug groove and the second lug groove. Since such a 1st sipe suppresses the fall of the whole rigidity of the said rib, the high turning performance on a wet road surface is maintained.

It is an expanded view of the tread part of the pneumatic tire of one embodiment of the present invention. FIG. 2 is a partially enlarged view near the tire equator of FIG. 1. It is AA sectional drawing of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a development view of a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1. In the present embodiment, a tire for a passenger car is shown as the tire 1, but it goes without saying that tires of various categories such as for heavy loads and motorcycles are included.

  As shown in FIG. 1, the tire 1 includes at least three main grooves 3 that extend continuously in the tire circumferential direction, for example, three main grooves 3 in the present embodiment. The main groove 3 includes, for example, a central center main groove 3C extending on the tire equator C and shoulder main grooves 3S on both sides thereof.

  The tire 1 includes at least one rib 4 that extends continuously in the tire circumferential direction on the tread portion 2, in the present embodiment. The rib 4 of this embodiment includes a middle rib 5 partitioned between the center main groove 3C and the shoulder main groove 3S, and a shoulder rib 6 partitioned between the shoulder main groove 3S and the tread end Te. Yes. The middle ribs 5 of the present embodiment are provided on both sides of the tire equator C, respectively.

  The “tread end” is the outermost end in the tire axial direction of the tread contact surface when the normal tire 1 is loaded with a normal load and brought into contact with a plane at a camber angle of 0 °.

  The “normal state” is a state in which the tire 1 is assembled on a normal rim (not shown) and filled with a normal internal pressure and is not loaded.

  The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire 1 is based. For example, “Standard Rim” for JATMA and “Design Rim” for TRA. "If it is ETRTO, it is" Measuring Rim ".

  The “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire 1 is based. For example, “maximum air pressure” for JATMA, and table for TRA. The maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” for ETRTO.

  The “regular load” is a load determined by each standard for each tire in a standard system including a standard on which the tire 1 is based. For example, “maximum load capacity” for JATMA, and “TRA” for TRA. The maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES", "LOAD CAPACITY" for ETRTO.

  FIG. 2 shows a partially enlarged view in which the vicinity of the tire equator C in FIG. 1 is enlarged. FIG. 3 is a cross-sectional view taken along the line AA in FIG. In this specification, when there is no notice in particular, the dimension of each part of the tire 1 is a value in a normal state.

  As shown in FIG. 2 or FIG. 3, the groove width W4 and the groove depth D4 of the main groove 3 are not particularly limited in the present embodiment. Is done. The groove width W4 of the main groove 3 is, for example, in the range of 3.0 to 8.0% of the tread width TW (shown in FIG. 1) between the tread ends Te and Te from the viewpoint of rigidity or drainage of the tread portion 2. It is desirable that

  The groove depth D4 of the main groove 3 is desirably in the range of 6.0 to 9.0 mm, for example, from the same viewpoint as the groove width W4. The main groove 3 is provided in a straight line in the present embodiment from the viewpoint of drainage and straight running stability, but may be, for example, a zigzag.

  As shown in FIG. 2, each middle rib 5 includes a plurality of first lug grooves 8, a plurality of second lug grooves 9, and a plurality of sipes 10 that do not communicate with the first lug grooves 8 and the second lug grooves 9. And are provided.

  The first lug groove 8 extends from the rib edge 5a on one side of the middle rib 5 in the tire axial direction, in the present embodiment, on the tire equator C side. The second lug groove 9 extends from the rib edge 5b on the other side of the middle rib 5 in the tire axial direction, in this embodiment, on the outer side in the tire axial direction. The first lug groove 8 and the second lug groove 9 have end points 8e and 9e in the middle rib 5, respectively.

  The first lug groove 8 and the second lug groove 9 are inclined in the same direction with respect to the tire circumferential direction. For this reason, the traction performance during straight traveling is improved by the edge effect. Moreover, on the wet road surface, the water film between the road surface and the tread portion 2 can be efficiently drained from the rib edge 5a side or the rib edge 5b side of the middle rib 5 to the main groove 4, and the traction performance on the wet road surface can be further improved. Further improve.

  The first lug groove 8 and the second lug groove 9 are disposed at positions facing the middle rib 5 in the tire axial direction. More specifically, the 1st lug groove 8 and the 2nd lug groove 9 should just be distribute | arranged so that it may cross | intersect on the arbitrary straight lines along a tire axial direction, for example. Such first lug groove 8 and second lug groove 9 reduce the rigidity in the vicinity of first lug groove 8 and second lug groove 9 of middle rib 5. In order to lower the rigidity of the middle rib 5 more partially, it is desirable that 80% or more of the tire circumferential direction components of the first lug groove 8 face the second lug groove 9.

  The sipe 10 includes a first sipe 11 that is inclined with respect to the tire equator C in a direction opposite to the first lug groove 8 and the second lug groove 9. The first sipe 11 is provided between the first lug groove 8 and the second lug groove 9 that face each other in the tire axial direction.

  The first sipe 11 further reduces the rigidity of the middle rib 5 in the vicinity of the first lug groove 8 and the second lug groove 9 that face each other in the tire axial direction. For this reason, deformation of the rib edge 5c of the middle rib 5 connected to the first lug groove 8 and the second lug groove 9 is facilitated, and uneven wear at the rib edge 5c is suppressed. Further, the first sipe 11 does not communicate with the first lug groove 8 and the second lug groove 9. Such a 1st sipe 11 can suppress the fall of the whole rigidity of the middle rib 5, and the high turning performance on the wet road surface of the tire 1 is maintained.

  In a preferred embodiment, the first sipe 11 extends linearly. For example, the first sipe 11 is arranged on a straight line connecting the first lug groove 8 and the second lug groove 9 facing each other in the tire axial direction. Such a first sipe 11 effectively reduces the rigidity of the middle rib 5 in the vicinity of the first lug groove 8 and the second lug groove 9. In particular, the first sipe 11 is preferably arranged on a straight line connecting the end 8e of the first lug groove 8 and the end 9e of the second lug groove 9 facing each other in the tire axial direction.

  The groove width and groove depth of the sipe 10 are not particularly limited in the present embodiment, and, for example, those within the range listed in the customary manner are preferably used.

  The sipe 10 includes, for example, a second sipe 12 disposed between the first sipe 11 adjacent in the tire circumferential direction. The second sipe 12 serves to adjust the rigidity of the middle rib 5.

  The second sipe 12 includes, for example, a first component 12a inclined in the same direction as the first sipe 11, a circumferential component 12b extending in the tire circumferential direction on the inner side in the tire axial direction of the first component 12a, and the first component 12a. And an axial component 12c extending outward in the tire axial direction. The circumferential component 12b can adjust the axial rigidity of the middle rib 5, and can improve the turning performance by the edge effect. The axial direction component 12c can adjust the circumferential rigidity of the middle rib 5, and can improve the traction performance due to the edge effect.

  It is desirable that the first lug groove 8 and the second lug groove 9 are inclined at an angle α of 45 to 70 °, for example, with respect to the tire circumferential direction. When the angle α is less than 45 °, the edge effect of the first lug groove 8 and the second lug groove 9 is difficult to be exhibited, and it is difficult to sufficiently improve the traction performance. On the other hand, when the angle α is larger than 70 °, it is difficult to drain into the main groove 4 and it is difficult to exhibit sufficient drainage.

  The ratio (L1 / W1) between the length L1 in the longitudinal direction of the first lug groove 8 and the width W1 in the tire axial direction of the middle rib 5 is preferably in the range of 0.3 to 0.5, for example. When the value of the ratio (L1 / W1) is less than 0.3, not only is it difficult to improve drainage, but the rigidity of the middle rib 5 may not be sufficiently reduced. Conversely, when the value of the ratio (L1 / W1) is greater than 0.5, the rigidity of the middle rib 5 may be extremely reduced.

  The ratio (L2 / W1) between the length L2 in the longitudinal direction of the second lug groove 9 and the width W1 of the middle rib 5 is, for example, 0.3 to 0.5 from the same viewpoint as the ratio (L1 / W1). It is desirable to be in the range.

  As shown in FIG. 3, the groove depths of the first lug groove 8 and the second lug groove 9 are gradually reduced toward the terminal ends 8e and 9e, for example. In such a 1st lug groove 8 and the 2nd lug groove 9, the water film between a road surface can be drained to the main groove 4 along the groove bottom which inclines, and drainage property can be improved further.

  The ratio (D2 / D1) of the depth D1 on the rib edge 5a, 5b side of the first lug groove 8 and the second lug groove 9 to the depth D2 on the terminal end 8e, 9e side is 0.4 to 0.6. A range is desirable. When the value of the ratio (D2 / D1) is less than 0.4, the slope of each groove bottom of the first lug groove 8 and the second lug groove 9 is small, and there is a possibility that the drainage performance cannot be improved. On the other hand, when the value of the ratio (D2 / D1) is larger than 0.6, the inclination of the groove bottoms of the first lug groove 8 and the second lug groove 9 is large, and the depth D2 on the end 8e, 9e side is Get smaller. For this reason, it becomes difficult to introduce the water film between the road surface and the end 8e, 9e into the first lug groove 8 or the second lug groove 9, and the drainage performance may not be improved.

  As shown in FIG. 2, the shortest distance L3 from the end 8e of the first lug groove 8 or the end 9e of the second lug groove 9 to the first sipe 11 is, for example, in the range of 1.0 to 5.0 mm. It is desirable. When the shortest distance L3 is less than 1.0 mm, the rigidity of the middle rib 5 in the vicinity of the first lug groove 8 and the second lug groove 9 is greatly reduced, and uneven wear tends to occur in that portion. On the contrary, when the shortest distance L3 is larger than 5.0 mm, the rigidity of the middle rib 5 in the vicinity of the first lug groove 8 and the second lug groove 9 may not be sufficiently lowered, and the rib edge 5c is likely to be unevenly worn. .

  The middle rib 5 of the present embodiment desirably includes a chamfered portion 5d in which an acute angle portion formed by the first lug groove 8 or the second lug groove 9 and each rib edge 5a, 5b is chamfered with a slope. . The chamfered portion 5d is useful for suppressing cracks at the acute angle portion.

  As shown in FIG. 1, the tire 1 of the present embodiment includes a buttress region 20 that continues from the tread end Te to the outer side in the tire axial direction. The buttress region 20 is provided with, for example, a buttress vertical groove 21 extending in the tire circumferential direction and a buttress lug groove 22 extending from the buttress vertical groove 21 inward in the tire axial direction.

  The buttress lug groove 22 is provided in, for example, a linear shape or an arc shape extending from the buttress longitudinal groove 21 inward in the tire axial direction. The buttress lug grooves 22 include first buttress lug grooves 22A and second buttress lug grooves 22B that are alternately arranged in the tire circumferential direction. The first buttress lug groove 22A has a terminal end on the inner side in the tire axial direction than the tread end Te. The first buttress lug groove 22A is useful for improving the traction performance due to the edge effect.

  The second buttress lug groove 22B has a terminal end on the outer side in the tire axial direction from the tread end Te. The second buttress lug groove 22B terminates in the buttress area 20 and is deformed in such a direction that the groove width widens at the time of grounding. For this reason, the contact pressure on the contact end side of the shoulder rib 6 is reduced, and the heat generation of the shoulder rib 6 is suppressed.

  As mentioned above, although especially preferable embodiment of this invention was described in full detail, this invention is not limited to this embodiment, It can deform | transform and implement in a various aspect.

  Tires having the basic pattern shown in FIG. 1 and based on the specifications in Table 1 were prototyped and tested. The main common specifications of tires are as follows.

Tire size: 195 / 65R15
Rim: 6.00JJ
Tread width TW: 140 mm
Each test method is as follows.

<Wet braking performance>
Each sample tire was mounted on all the wheels of the vehicle, and was run on a wet road surface in which a water film was formed on the road surface under the conditions of the front wheel internal pressure (230 kPa) and the rear wheel internal pressure (220 kPa). Then, when the travel speed reached 100 km / h, the ABS brake was operated, the distance from the position where the ABS brake was operated to the stop position of the vehicle was measured, and the comparative example 1 was evaluated with an index of 100. The larger the value, the better the wet braking performance and the better the traction performance on the wet road surface.

<Wet turning performance>
Each sample tire was mounted on all the wheels of the vehicle, and was run on a wet road surface in which a water film was formed on the road surface under the conditions of the front wheel internal pressure (230 kPa) and the rear wheel internal pressure (220 kPa). And the turning performance at the time of driving | running | working was evaluated by the index | index which makes Comparative Example 1 100 based on the sensory evaluation of a driver. The larger the value, the better the turning performance on the wet road surface.

<Uneven wear resistance>
Each sample tire was mounted on all the wheels of the vehicle under the condition of internal pressure (180 kPa) and traveled in the city area for 20,000 km. And the shoulder fall wear and H & T wear of the tire after driving | running | working were determined visually, and the comparative example 1 was evaluated by the index | exponent which set it as 100 based on the determination result. The larger the value, the less uneven wear and the better anti-wear performance.

  As shown in Table 1, it was confirmed that the tires of the examples had improved wear resistance while maintaining the turning performance on the wet road surface, and further improved the traction performance on the wet road surface.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Main groove 4 Rib 5 Middle rib 8 1st lug groove 9 2nd lug groove 10 Sipe 11 1st sipe C Tire equator

Claims (12)

A pneumatic tire including at least one rib extending continuously in a tire circumferential direction in a tread portion,
The at least one rib includes a plurality of first lug grooves extending from a rib edge on one side in the tire axial direction of the rib and terminating in the rib, and extending from a rib edge on the other side in the tire axial direction of the rib. And a plurality of second lug grooves having terminations in the ribs, and a plurality of sipes not communicating with the first lug grooves and the second lug grooves,
The first lug groove and the second lug groove are inclined in the same direction with respect to the tire circumferential direction, and
The first lug groove and the second lug groove are arranged at positions where 80% or more of the tire circumferential direction component of the first lug groove faces the second lug groove in the tire axial direction,
The sipe is provided between the first lug groove and the second lug groove that are inclined to the other side opposite to the first lug groove and the second lug groove and face each other in the tire axial direction. A pneumatic tire comprising the first sipe.
  2. The pneumatic tire according to claim 1, wherein the first sipe is disposed on a straight line connecting the first lug groove and the second lug groove facing in the tire axial direction.   The pneumatic tire according to claim 1 or 2, wherein the first sipes are arranged on a straight line connecting the end of the first lug groove and the end of the second lug groove facing in the tire axial direction. .   The sipe includes a second sipe that is disposed between the first sipe adjacent in the tire circumferential direction and has a first component that is inclined in the same direction as the first sipe. The described pneumatic tire.   The second sipe has a circumferential component extending in the tire circumferential direction on the inner side in the tire axial direction of the first component, and an axial component extending on the outer side in the tire axial direction on the outer side in the tire axial direction of the first component. 4. The pneumatic tire according to 4. The tread portion includes at least three main grooves extending continuously in the tire circumferential direction,
The pneumatic tire according to any one of claims 1 to 5, wherein the ribs are middle ribs divided between the main grooves and disposed on one side or the other side of the tire equator.   The pneumatic tire according to any one of claims 1 to 6, wherein the first lug groove and the second lug groove are inclined at an angle of 45 to 70 ° with respect to a tire circumferential direction.   The ratio (L1 / W1) between the length L1 in the longitudinal direction of the first lug groove and the width W1 in the tire axial direction of the rib, and the length L2 in the longitudinal direction of the second lug groove and the rib The pneumatic tire according to any one of claims 1 to 7, wherein a ratio (L2 / W1) to the width W1 is in a range of 0.3 to 0.5.   The pneumatic tire according to any one of claims 1 to 8, wherein a groove depth of the first lug groove and the second lug groove gradually decreases toward the terminal end side.   The ratio (D2 / D1) of the depth D1 on the rib edge side and the depth D2 on the end side of the first lug groove and the second lug groove is in a range of 0.4 to 0.6. 9. The pneumatic tire according to 9.   11. The shortest distance L <b> 3 from the end of the first lug groove or the end of the second lug groove to the first sipe is in a range of 1.0 to 5.0 mm. Pneumatic tires.   The pneumatic tire according to any one of claims 1 to 11, wherein the rib includes a chamfered portion in which an acute angle portion formed by the first lug groove or the second lug groove and each rib edge is chamfered. .

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