JP5780854B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire provided with a land portion extending along a tire circumferential direction on a tread.

  Various pneumatic tires have been proposed in which a tread includes a land portion extending along a tire circumferential direction defined by circumferential grooves (see, for example, Patent Document 1).

Pneumatic tires mounted on ordinary vehicles are given a negative camber, and the tread has a contact pressure on the inner side in the tire width direction when the vehicle is mounted is greater than a contact pressure on the outer side in the tire width direction when the vehicle is mounted. Further, the ground contact shape is longer on the inner side in the tire width direction when the vehicle is mounted than on the outer side in the tire width direction when the vehicle is mounted.
For this reason, in the rib-shaped land portion extending in the tire circumferential direction arranged at the innermost side in the vehicle width direction when the vehicle is mounted, wear near the circumferential groove is more easily promoted by traction than other portions, so-called uneven wear is caused. It tends to occur.
Moreover, in a pneumatic tire, in order to improve wet performance and on-ice performance, it is generally performed to form a sipe in a land portion.
Pneumatic tires require braking and traction, but they also need slip suppression during cornering, so they have an edge component in the tire width direction that works on braking and traction, and an edge component in the tire circumferential direction that works on lateral force. An inclined sipe that is inclined with respect to the tire width direction is formed on the land portion.

JP 2003-154815 A

  Since pneumatic tires are particularly slippery on road surfaces with a low coefficient of friction (road surfaces with a particularly low coefficient of friction are called low mu roads), the market demands further improvements in driving performance on wet road surfaces with a particularly low coefficient of friction. It has been. Also, with pneumatic tires mounted on negative camber vehicles, wear of the land portion on the inner side in the vehicle width direction when the vehicle is mounted is particularly accelerated compared to other land portions such as the land portion on the outer side in the vehicle width direction. It tends to be easily done.

  In consideration of the above facts, the present invention tends to promote further improvement in running performance on a slippery wet road surface having a particularly low friction coefficient and wear of a land portion extending in the tire circumferential direction inside the vehicle width direction when the vehicle is mounted. It is an object to provide a pneumatic tire capable of improving the above.

As a result of various experimental studies by the inventor, uneven wear caused by a land portion extending in the tire circumferential direction disposed on the innermost side in the vehicle width direction when the vehicle is mounted is caused by imbalance of the contact pressure in the tire width direction of the tread and the contact shape. In addition, it was found that the difference in ground pressure in the land was also related.
Furthermore, the edge effect is effective for improving the wet performance on wet road surfaces with a particularly small coefficient of friction (such as flat road surfaces with little unevenness). The position of the sipe formed on the land and the direction in which the sipe extends are determined. It has been found that by optimizing, it is possible to secure wet performance on a wet road surface with a particularly small friction coefficient and wet performance on a wet road surface with a relatively large friction coefficient while suppressing uneven wear.

This invention is made | formed in view of the said fact, Comprising: The pneumatic tire of Claim 1 makes the land part extended along the tire circumferential direction divided by the circumferential groove at the time of vehicle mounting | wearing of a tread. In the vehicle width direction innermost side, the land portion has a high angle sipe extending incline with respect to the tire width direction on the innermost circumferential groove side in the vehicle width direction, and the tire width direction from the high angle sipe. Are formed alternately in the tire circumferential direction, and the circumferential groove disposed on the innermost side in the vehicle width direction includes the circumferential groove and the high angle sipe. A bottom-up protrusion is provided that is connected to a side portion of the acute angle portion of the land portion to be formed and reinforces the acute angle portion .

By attaching the pneumatic tire of claim 1 to a negative camber vehicle, the following effects can be obtained.
When the pneumatic tire of claim 1 is attached to a negative camber vehicle, the pneumatic tire is tilted so that the upper portion of the tire is on the inner side of the vehicle with respect to the lower portion when viewed from the front of the vehicle. As a result, the contact pressure of the tread is higher in the region on the inner side in the vehicle width direction than the region on the outer side in the vehicle width direction than the tire equator surface, and the contact length is on the inner side in the vehicle width direction with respect to the tire equator surface. Becomes longer than the outside in the vehicle width direction.

  Therefore, in the tread, the land portion on the inner side in the vehicle width direction has a higher contact pressure and a longer contact length compared to the land portion on the outer side in the vehicle width direction when the vehicle is mounted. In the near land portion, the ground pressure on the adjacent circumferential groove (the innermost circumferential groove in the vehicle width direction) tends to increase, but the land portion has a high angle sipe on the adjacent circumferential groove side. By alternately forming the low-angle sipe in the tire circumferential direction, the rigidity of the land portion on the circumferential main groove side can be reduced, and an increase in the contact pressure on the circumferential main groove side of the land portion can be suppressed, The promotion of wear on the circumferential groove side of the land portion can be suppressed.

  In addition, since the land portion where the low-angle sipe and the high-angle sipe having the edge component in the tire width direction are alternately formed is provided on the innermost side in the vehicle width direction where the contact length becomes longer, the tire width in the contact surface The edge component in the direction can be increased efficiently, and high wet performance can be obtained on a slippery wet road surface with a particularly low friction coefficient.

Since high-angle sipe has many edge components in the tire circumferential direction (compared to the edge component in the tire width direction), pneumatic tires have a high grip when cornering on slippery wet road surfaces with a particularly low coefficient of friction. Force can be obtained and side slip can be effectively suppressed.
In the land portion, the acute angle portion has a lower rigidity than other portions (a portion having a larger angle than the acute angle portion, for example, a right angle portion or an obtuse angle portion) and is easily deformed. By providing and reinforcing the acute angle portion, the rigidity of the acute angle portion can be improved and deformation of the acute angle portion can be suppressed. Improving the rigidity of the acute angle portion to suppress deformation leads to securing the ground contact area of the land portion, preventing uneven wear of the land portion, and the like, and is a preferable mode.

The invention according to claim 2 is the pneumatic tire according to claim 1, wherein an angle of the low-angle sipe with respect to a tire width direction is set to 15 ° or less, and the groove depth of the low-angle sipe is The groove depth of the high angle sipe is set within a range of 20 to 80% of the groove depth of the circumferential groove, and the angle of the high angle sipe with respect to the tire width direction is set within a range of 45 to 75 °. Is set within a range of 20 to 50% of the groove depth of the circumferential groove.

Next, the operation of the pneumatic tire according to claim 2 will be described.
As will be described later using Examples and Comparative Examples, when the angle of the low-angle sipe with respect to the tire width direction exceeds 15 °, it is difficult to prevent uneven wear.
Further, if the groove depth of the low angle sipe is 20% less than the groove depth of the circumferential groove, the effect of preventing uneven wear is reduced, and the groove depth of the low angle sipe is less than the groove depth of the circumferential groove. If it exceeds 50%, the shoulder block rigidity is significantly lowered, and the cornering performance and the like are deteriorated.

If the angle of the high-angle sipe with respect to the tire width direction is less than 45 °, the edge effect is reduced by shortening the sipe and the braking performance is weakened. If the angle of the high-angle sipe with respect to the tire width direction exceeds 74 °, the sipe The effect of capturing the road surface becomes smaller, and the braking performance becomes weaker.
Further, when the groove depth of the high angle sipe is 20% less than the groove depth of the circumferential groove, the edge effect is reduced and the braking performance is weakened.
When the groove depth of the high-angle sipe exceeds 80% of the groove depth of the circumferential groove, the shoulder block rigidity is significantly lowered, and the cornering performance and the like are deteriorated.

According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, the size of the bottom raised protrusion in the tire width direction is smaller than the groove width of the circumferential groove, and the bottom raised protrusion The tread plan view shape is an isosceles trapezoid in which the upper base is disposed on the groove side and the lower base is disposed on the acute angle portion side.

Next, the operation of the pneumatic tire according to claim 3 will be described .
When traveling on snow, the snow is clogged in the circumferential groove and a snow column is formed in the circumferential groove. At the time of braking or traction, this snow column tends to shift in the circumferential direction in the circumferential groove, but the snow column hits the bottom raising protrusion in the circumferential groove, so that the displacement is suppressed, so Snow traction performance is improved. In addition, since the tread plan view shape of the bottom raising protrusion is an isosceles trapezoid, the effect of preventing the deviation of the snow column does not differ depending on the moving direction of the snow column.

Therefore, both the snow braking performance and the snow traction performance can be improved equally, and even if the pneumatic tire on the left side of the vehicle and the pneumatic tire on the right side of the vehicle are replaced, the performance on the snow does not change.
Furthermore, by making the bottom raised protrusion like this isosceles trapezoid, the resistance does not differ depending on the direction of the water flowing in the circumferential groove, and the pneumatic tire on the left side of the vehicle and the pneumatic tire on the right side of the vehicle are exchanged. But drainage does not change.
Therefore, it is not necessary to specify the rotational direction of the pneumatic tire.

According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the acute angle portion is formed with a chamfer that is inclined toward an acute angle tip portion.
Next, the operation of the pneumatic tire according to claim 4 will be described .
Since the acute angle part is a part with particularly low rigidity on the tip side, by forming a chamfer that slopes toward the acute angle tip part, the particularly low rigidity part is removed, and the rigidity of the land part is secured. I can do it.

According to a fifth aspect of the present invention, in the pneumatic tire according to any one of the first to fourth aspects, the high angle sipe and the low angle sipe each open in a circumferential groove. .

Next, the operation of the pneumatic tire according to claim 5 will be described .
By opening the high-angle sipe and the low-angle sipe in the circumferential groove, the water in the sipe can be drained into the circumferential groove when traveling on a wet road surface, and the wet performance can be improved.

As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it has a high wet performance on a slippery wet road surface with a particularly low friction coefficient, and wear of a land portion on the inner side in the vehicle width direction when the vehicle is mounted. It has an excellent effect that it is possible to simultaneously improve the tendency to be promoted. In addition, the acute angle portion formed by the high-angle sipe and the circumferential groove can be reinforced by the raised bottom protrusion, and the rigidity of the land portion can be ensured.

  Since the pneumatic tire according to claim 2 has the above-described configuration, it is possible to suppress wear of a land portion on the shoulder side on the outer side in the vehicle width direction when the vehicle is mounted, and to improve wet performance on a slippery wet road surface having a particularly low friction coefficient. Can be achieved at a high level.

Since the pneumatic tire according to claim 3 has the above-described configuration, it is not necessary to specify the rotation direction.

Since the pneumatic tire according to claim 4 has the above-described configuration, the rigidity of the land portion can be ensured even if it has an acute angle portion.

The pneumatic tire according to claim 5 has an excellent effect that wet performance can be further improved.

It is a top view of the tread of the pneumatic tire concerning one embodiment of the present invention. It is an enlarged plan view of the tread near the inclined land portion. It is a perspective view which shows a part of inclined land part. It is sectional drawing of the 1st circumferential direction groove | channel. It is an enlarged plan view of a 2nd land part and an in side shoulder land part.

Hereinafter, a pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 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, 2009 edition) and applicable size / prior 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.

  Further, the pneumatic tire 10 of the present embodiment has a left-right asymmetric pattern shape with the tire equatorial plane CL in between, the right side in the drawing is the inside when the vehicle is mounted (indicated by an arrow IN), and the left side in the drawing is when the vehicle is mounted. It is mounted on the vehicle so as to be outside (indicated by an arrow OUT). The pneumatic tire 10 has no designation of the rotation direction, but the left and right mounting directions are designated. Therefore, marks such as INSIDE (inside) and OUTSIDE (outside) are given to the side portion of the pneumatic tire 10, for example.

  In the tread 12 of the pneumatic tire 10 of the present embodiment, a first circumferential groove 14 and a second circumferential groove 16 are a plurality of (three in the present embodiment) circumferential grooves extending along the tire circumferential direction. And the 3rd circumferential direction groove | channel 18 is formed.

  The first circumferential groove 14 is disposed on one side of the tire equatorial plane CL (outside when mounted on the vehicle: OUT side), and the second circumferential groove 16 and the third circumferential groove 18 are the other of the tire equatorial plane CL. It is arranged on the side (inside when the vehicle is mounted: IN side). Further, the second circumferential groove 16 is disposed on the tire equatorial plane CL side with respect to the third circumferential groove 18. The first circumferential groove 14 is the outermost circumferential groove on the OUT side, and the third circumferential groove 18 is the outermost circumferential groove on the IN side. The second circumferential groove 16 is formed at a position closer to the tire equatorial plane CL than the first circumferential groove 14.

  A land portion 20 is formed between the first circumferential groove 14 and the second circumferential groove 16. In the land portion 20, a plurality of inclined grooves 30 are formed in the circumferential direction so as to cross the first circumferential groove 14 and the second circumferential groove 16. The inclined groove 30 extends from the first circumferential groove 14 to the second circumferential groove 16 so as to be inclined upward and communicates the first circumferential groove 14 and the second circumferential groove 16. ing.

  Since the second circumferential groove 16 is formed closer to the tire equatorial plane CL than the first circumferential groove 14, the center of the land portion 20 in the tire width direction is closer to the tire equatorial plane CL when the vehicle is mounted. It is located outside (arrow OUT direction side).

As shown in FIGS. 2 and 3, the inclined groove 30 has a shallow groove 30A having a groove bottom shallower than the central portion in the groove longitudinal direction on the second circumferential groove 16 side near the tire equatorial plane CL. The circumferential groove 14 side is a shallow groove 30B having a groove bottom shallower than the central portion in the groove longitudinal direction.
The shallow groove 30A of the present embodiment extends to the first circumferential groove 14 side from the tire equatorial plane CL, and is connected to a shallow groove 36A of a second sub groove 36 described later.

  As shown in FIG. 2, the inclined groove 30 is directed from the second circumferential groove 16 side toward the first circumferential groove 14 side located on the outer side (arrow OUT direction side) when the vehicle is mounted than the tire equatorial plane CL. The groove width is formed so as to be gradually increased, and the drainage to the first circumferential groove 14 side is facilitated. The inclined groove 30 has a curved shape that slightly bulges to the lower right side of the figure.

  The angle of the inclined groove 30 with respect to the tire equatorial plane CL is preferably in the range of 20 ° to 60 °. If the angle is less than 20 °, an inclined land portion 22 to be described later becomes too long in the tire circumferential direction, and there is a concern about deterioration of motion performance. On the other hand, when the angle of the inclined groove 30 with respect to the tire circumferential direction exceeds 60 °, there is no merit for drainage performance. Therefore, the angle of the inclined groove 30 with respect to the tire equatorial plane CL is preferably in the range of 20 ° to 60 °.

  An inclined land portion 22 is formed between adjacent inclined grooves 30. The corner portion 24 of the inclined land portion 22 has a sharper angle than the corner portion 26. The corner portion 24 is formed with a chamfer 24A that is inclined toward the acute tip portion, and a portion having low rigidity is removed.

  On the side of the inclined land portion 22 in the direction of arrow A, a step portion 40 is formed between the shallow groove 30A and the shallow groove 30B so as to face the inclined groove 30. The step portion 40 is formed so as to fill the corner from the shallow groove 30A to the shallow groove 30B of the inclined land portion 22.

  As shown in FIG. 3, the step portion 40 has a step surface 42 that rises from the groove bottom of the inclined groove 30 and is lower than the tread surface of the inclined land portion 22. In the present embodiment, the step surface 42 of the step portion 40, the groove bottom of the shallow groove 30A, and the groove bottom of the shallow groove 30B are flush with each other (the same height).

The sipe 38A-1, sipe 38A-2, and the second sub-portion from the second circumferential groove 16 side to the first circumferential groove 14 side are connected to the inclined land portion 22 so as to connect the adjacent inclined grooves 30 to each other. A groove 36, a sipe 38B, a first sub-groove 34, and a sipe 38C are formed in this order. Note that the sipe 38A-1, sipe 38A-2, sipe 38B, and sipe 38C have groove widths that are closed when the inclined land portion 22 comes into contact with the road surface. The second sub-groove 36 is set to a groove width that does not close at the time of grounding.
In the second sub-groove 36, a part of the tire equatorial plane CL side is a shallow groove 36A whose groove bottom is shallower than the side opposite to the tire equatorial plane CL. The groove depth is the same as the shallow groove 30A.

With respect to the height dimension of the inclined land portion 22 (measured from the groove bottoms of the first circumferential groove 14 and the second circumferential groove 16; 9.8 mm in this embodiment), each sipe formed in the inclined land portion 22 The depth dimension is preferably in the range of 40 to 80%, and is 7.1 mm in this embodiment.
Further, each sipe formed on the inclined land portion 22 has a narrow groove width that closes when the inclined land portion 22 contacts the road surface, and is preferably within a range of 0.3 to 1.0 mm as an example. It is set to 0.7 mm.

  In the tread plan view, these sipe 38A-1, sipe 38A-2, second sub-groove 36, sipe 38B, first sub-groove 34, and sipe 38C are on one side in the tire circumferential direction, which is a drawing in this embodiment. It is made into the circular arc shape which becomes convex in the arrow A direction side.

Here, in the pneumatic tire 10 of the present embodiment, the groove cross-sectional area of the first sub-groove 34 (groove volume per unit length) and the groove cross-sectional area of the second sub-groove 36 (groove per unit length). The second sub-groove 36 formed at a position close to the tire equator plane CL is more than the first sub-groove 34 formed at a position far from the tire equator plane CL. The groove width is relatively narrow and the groove depth is deep.
However, both the first sub-groove 34 and the second sub-groove 36 need to allow snow to enter the groove when traveling on snow.

Further, the first sub-groove 34 and the second sub-groove 36 of the present embodiment have the widest groove width on the tire equatorial plane CL side, and the groove width gradually decreases toward the opposite side of the tire equatorial plane CL. ing.
The first sub-groove 34 preferably has a groove depth within the range of 10 to 40% of the height of the inclined land portion 22 and a groove width within the range of 1.0 to 5.0 mm. On the other hand, the second sub-groove 36 preferably has a groove depth within a range of 40 to 80% of a height of the inclined land portion 22 and a groove width within a range of 1.0 to 5.0 mm. .
The first sub-groove 34 of the present embodiment has a minimum groove width of 2 mm and a maximum groove width of 5 mm. The second sub-groove 36 of the present embodiment has a minimum groove width of 2 mm and a maximum groove width of 6 mm.

  As shown in FIG. 2, in the present embodiment, bottom-up portions 34 </ b> A that protrude from the groove bottom and connect land portions on both sides of the groove are formed at both longitudinal ends of the first sub-groove 34.

  Here, the sipe 38A-1, sipe 38A-2, sipe 38B, and sipe 38C formed in the inclined land portion 22 of the present embodiment are arc-shaped in a tread plan view, but as shown in FIG. The radius of curvature R is preferably 50 mm or less. The sipe 38A-1, sipe 38A-2, sipe 38B, and sipe 38C are preferably formed generally in the tire width direction, and a virtual line FL that linearly connects one end and the other end of the sipe longitudinal direction. Is preferably 30 ° or less, and is preferably 45 ° or less throughout the sipe.

  Note that the orientation, shape, and radius of curvature of the first sub-groove 34 and the second sub-groove 36 are also defined in the same manner as the sipe 38A-1, sipe 38A-2, sipe 38B, and sipe 38C. preferable.

As shown in FIG. 2, a first protrusion 46 that protrudes into the first circumferential groove 14 is formed on the corner portion 24 side of the inclined land portion 22.
The tread planar view shape of the first protrusion 46 is an isosceles trapezoid in which the upper base is disposed on the groove side and the lower base is disposed on the acute angle portion side, but may be other shapes. The dimension of the first protrusion 46 in the tire width direction is preferably smaller than the groove width of the first circumferential groove 14 in consideration of the flow of water when traveling on a wet road surface.

As shown in FIG. 4, the first protrusion 46 has a triangular shape as viewed from the tire circumferential direction, but may have another shape such as a rectangle. When running on the snow, the snow that has entered the first circumferential groove 14 is restrained from shifting in the longitudinal direction of the groove by being caught by the first protrusion 46 protruding into the groove, and braking performance and traction on the snow are suppressed. Performance can be improved. Further, the first protrusion 46 can improve the rigidity by reinforcing the acute corner 24 of the inclined land portion 22. Since the first protrusion 46 is disposed on the outer side in the vehicle width direction when the tire corner vehicle is mounted on the acute corner portion 24, the first protrusion portion 46 is particularly effective for suppressing deformation of the acute corner portion 24 toward the first circumferential groove 14 side. It is effective.
In order to further reinforce the acute corner portion 24 of the inclined land portion 22, the inclined groove 30 includes a shallow groove 30B in which a portion of the first circumferential groove 14 side is shallower than the intermediate portion in the groove longitudinal direction. It has become.

  As shown in FIG. 5, a second land portion 50 is formed between the second circumferential groove 16 and the third circumferential groove 18. A groove-like sound absorbing cavity 52 extending along the tire circumferential direction is formed at the center of the second land portion 50 in the tire width direction. The sound absorbing cavity 52 is communicated with the second circumferential groove 16 through a sound absorbing shallow groove 54 that is inclined with respect to the tire circumferential direction. The volume of the sound-absorbing cavity 52 and the cross-sectional area and length of the sound-absorbing shallow groove 54 are set based on the Helmholtz resonance theory so that the resonance frequency is reduced so as to reduce the noise in the second circumferential groove 16 generated during traveling. Has been.

In the second land portion 50, an acute angle portion 55 is formed by the sound absorption cavity portion 52 and the sound absorption shallow groove 54, and a first chamfer 55A inclined toward the acute angle tip portion is formed at the tip of the acute angle portion 55. The formed low rigidity portion is removed.
The acute angle portion 55 is formed with a second chamfer 55B along the sound absorbing cavity portion 52, and a portion having low rigidity is removed.

  In addition, the second land portion 50 is connected to the third circumferential groove 18 side of the sound absorption cavity 52, and one end thereof communicates with the third circumferential groove 18 and is not communicated with the sound absorption cavity 52. 56 is formed. An acute angle portion 57 is formed in the second land portion 50 by the sipe 56 and the third circumferential groove 18, and a third chamfer 57 </ b> A inclined toward the acute angle tip portion is formed at the tip of the acute angle portion 57. The formed low rigidity portion is removed.

  Furthermore, an acute corner 51 is formed at a portion where the sound absorbing shallow groove 54 and the second circumferential groove 16 of the second land portion 50 intersect. At the tip of the acute corner 51, a fourth chamfer 51A that is inclined toward the tip of the acute corner is formed, and a portion having low rigidity is removed.

In the second circumferential groove 16, a second protrusion 58 that projects into the second circumferential groove 16 is formed on the side of the acute corner 51. The second protrusion 58 has substantially the same shape as the first protrusion 46, can improve braking performance on snow and traction performance, and reinforces the sharp corner 51 to improve rigidity. be able to.
In addition, since the 2nd protrusion 58 is arrange | positioned at the vehicle width direction outer side at the time of tire vehicle mounting | wearing of the acute corner 51, it suppresses the deformation | transformation of the acute corner 51 to the 2nd circumferential groove 16 side. (Incidentally, since the inner side in the vehicle width direction of the acute corner portion 51 when the tire vehicle is mounted is the center side of the second land portion 50, the acute corner portion 51 is deformed inward in the vehicle width direction. Is suppressed by the presence of the center side of the second land portion 50.

  The second land portion 50 is slightly inclined with respect to the tire width direction so as to cross the second land portion 50 between the sound absorbing cavities 52 and the sound absorbing cavities 52 in the tire width direction. An extending sipe 53 is formed.

  On the shoulder side of the third circumferential groove 18, a rib-shaped in-side shoulder land portion 60 extending in the tire circumferential direction is formed. A sipe 62 extending in the tire circumferential direction is formed at the middle portion in the tire width direction of the in-side shoulder land portion 60. Between the sipe 62 and the third circumferential groove 18, there are a high angle sipe 64 inclined with respect to the tire width direction and a low angle sipe 59 having a smaller inclination angle with respect to the tire width direction than the high angle sipe 64. They are alternately formed in the circumferential direction. The high angle sipe 64 and the low angle sipe 59 communicate with the sipe 62 and the third circumferential groove 18 and open.

The high angle sipe 64 preferably has an inclination angle with respect to the tire width direction within a range of 45 to 75 °, a groove depth of 2 to 8 mm, and 20 to 80% of a groove depth of the third circumferential groove 18. It is preferable to be within the range.
Further, since the high-angle sipe 64 is mainly intended to generate an edge effect, it is not always necessary to completely traverse the in-side shoulder land portion 60 and may be provided intermittently. In that case, a length of about 5 to 10 mm is sufficient.
On the other hand, the low-angle sipe 59 preferably has an inclination angle of 15 ° or less with respect to the tire width direction, within a range of a groove depth of 2 to 5 mm and a groove depth of 20 to 50% of the third circumferential groove 18. It is preferable that
The low-angle sipe 59 has a main purpose of preventing uneven wear, and is preferably set shallower than the high-angle sipe 64 in consideration of the balance with the cornering force.

The third circumferential groove 18 protrudes into the third circumferential groove 18 on the side of an acute corner 61 formed by the high-angle sipe 64 of the in-side shoulder land portion 60 and the third circumferential groove 18. A third protrusion 66 is formed. The third protrusion 66 has substantially the same shape as the second protrusion 58 and the first protrusion 46, and can improve braking performance and traction performance on snow. It can be reinforced to improve rigidity.
It should be noted that a chamfer 61A that is inclined toward the acute angle tip portion is formed at the tip of the corner portion 61, and a portion having low rigidity is removed.

  Since the third protrusion 66 is disposed on the outer side in the vehicle width direction of the acute corner portion 61 when the tire is mounted on the tire vehicle, it is possible to suppress the deformation of the acute corner portion 61 toward the third circumferential groove 18 side. This is particularly effective. (By the way, the inner side in the vehicle width direction of the sharp corner portion 61 when the tire vehicle is mounted is the center side of the in-side shoulder land portion 60, so that the acute corner portion 61 is deformed inward in the vehicle width direction. Is suppressed by the presence of the center side of the in-side shoulder land portion 60.

In the in-side shoulder land portion 60, a plurality of end shallow grooves 63 extending toward the ground contact end 12E are formed on the shoulder side of the sipe 62 in the tire circumferential direction. The end shallow groove 63 is arranged so as to extend along the tire width direction. In the in-side shoulder land portion 60, two sipes 65 and 67 are formed between the adjacent end shallow grooves 63 in parallel with the end shallow grooves 63.
Further, in the in-side shoulder land portion 60, a sipe 69 that extends in the tire circumferential direction that intersects the sipe 65 and 67, and connects the end shallow groove 63 and the end shallow groove 63, on the shoulder side of the sipe 62. Is formed.

As shown in FIG. 1, a rib-shaped out-side shoulder land portion 70 extending in the tire circumferential direction is formed on the shoulder side of the first circumferential groove 14. A plurality of shallow shallow grooves 73 extending in the tire width direction from the vicinity of the first circumferential groove 14 are formed in the outer shoulder land portion 70 in the tire circumferential direction.
In the out-side shoulder land portion 70, two sipes 75 are formed between the adjacent end shallow grooves 73 in parallel with the end shallow grooves 73.
Sipes 72 and 74 extending in the tire circumferential direction are formed at the middle portion of the outer shoulder land portion 70 in the tire width direction so as to intersect the sipe 75 and connect the end shallow groove 73 and the end shallow groove 73. Yes.

  The out-side shoulder land portion 70 is formed with a notch 79 near the end of the inclined groove 30 on the first circumferential groove 14 side. The out-side shoulder land portion 70 is formed with a sipe 76 that extends in the tire width direction that connects the end shallow groove 73 and the notch 79.

(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
The pneumatic tire 10 of the present embodiment has a designated orientation when mounted on the vehicle, and is mounted so that the out-side shoulder land portion 70 faces the outside of the vehicle as shown in FIG. 1 (OUTSIDE (outside)). The tire side portion to which the mark (not shown because it is a well-known technique is not shown) is attached so as to face the outside of the vehicle.

  When the pneumatic tire 10 is attached to a negative camber vehicle, the pneumatic tire 10 is tilted (for example, when viewed from the front of the vehicle, the tire upper portion is tilted so as to be inside the vehicle from the lower portion). The contact pressure is higher in the region on the inner side in the vehicle width direction than the region on the outer side in the vehicle width direction relative to the tire equator plane CL, and the contact length on the inner side in the vehicle width direction on the outer side in the vehicle width direction with respect to the tire equatorial plane CL It becomes longer than the contact length.

  Therefore, in the tread 12, the contact pressure of the in-side shoulder land portion 60 is high and the contact length becomes long as compared with the out-side shoulder land portion 70, and in particular, in the in-side shoulder land portion 60, Although the contact pressure tends to increase, a high-angle sipe 64 and a low-angle sipe 59 are alternately formed in the tire circumferential direction on the third circumferential groove 18 side in the in-side shoulder land portion 60 to form the third circumferential direction. Since the land portion rigidity on the groove 18 side is reduced, an increase in ground pressure on the third circumferential groove 18 side of the in-side shoulder land portion 60 is suppressed, and the third circumferential groove 18 of the in-side shoulder land portion 60 is suppressed. Promotion of side wear (due to high ground pressure) is suppressed.

  Further, the in-side shoulder land portion 60 in which the low-angle sipe 59 and the high-angle sipe 64 having an edge component in the tire width direction are alternately formed is provided on the innermost side in the vehicle width direction where the contact length becomes longer. Since the sipe 53 is formed in the second land portion 50 adjacent to the in-side shoulder land portion 60, an edge component in the tire width direction can be efficiently ensured in the contact surface, and the friction coefficient is particularly low. High wet performance can be obtained on a slippery wet road surface.

Further, since the high-angle sipe 64 has many edge components in the tire circumferential direction that are effective against the lateral force (as compared with the edge components in the tire width direction), the pneumatic tire 10 is slippery with a particularly low friction coefficient. On a wet road surface, a high grip force can be obtained during cornering, and side slip can be effectively suppressed.
Needless to say, the edge component can be effective even when traveling on ice.

  By the way, the sharp corner 61 in the in-side shoulder land 60 has a lower rigidity than the obtuse corner, and thus tends to be deformed. However, the corner 61 of the in-shoulder land 60 has a third protrusion. Since it is reinforced by the portion 66 and the chamfer 61A is formed, the deformation of the corner portion 61 is suppressed when the lateral force is input, and the ground contact area of the in-side shoulder land portion 60 is ensured. Adhesion is ensured. Therefore, the edge effect in the tire circumferential direction of the high angle sipe 64 of the in-side shoulder land portion 60 can be maximized during cornering. Furthermore, by setting the low-angle sipe 59 with a shallow depth between the high-angle sipe 64, even if the edge is increased, the block rigidity is not reduced too much and the road surface with a high coefficient of friction can be supported. Can do.

In the pneumatic tire 10 of the present embodiment, the three circumferential directions of the tread 12 include a first circumferential groove 14, a second circumferential groove 16, and a third circumferential groove 18 that extend along the tire circumferential direction. Since the inclined groove 30 inclined with respect to the tire width direction is formed so as to connect the first circumferential groove 14 and the second circumferential groove 16 while arranging the groove, the basic drainage Is secured.
Since the inclined groove 30 is formed so that the groove width becomes wider toward the first circumferential groove 14, drainage toward the first circumferential groove 14 can be improved.

  Since the inclined groove 30 of the present embodiment is curved in a direction in which the inclination angle with respect to the tire equatorial plane gradually increases toward the first circumferential groove 14 side, compared to the case where the inclined groove 30 is linear, The distance from the inclined groove 30 toward the first circumferential groove 14 can be shortened, and the drainage can be improved.

  When the pneumatic tire 10 of the present embodiment travels on snow, the groove component extending in the tire width direction, that is, the inclined groove 30 and the end shallow groove 63 extending inclined with respect to the tire width direction are mainly used. Since the snow enters into the edge shallow groove 73 and the first sub-groove 34 and the second sub-groove 36 formed in the inclined land portion 22 to generate a snow column shear force in the tire circumferential direction, Traction performance and braking performance can be obtained.

  In the pneumatic tire 10 of the present embodiment, the inclined land portion 22 is defined so as to cross the tread 12 near the center of the tread where the contact pressure is high, that is, the tire equatorial plane CL. Snow can easily enter the inclined grooves 30 and the second sub-grooves 36 and the first sub-grooves 34 formed at positions close to the tire equatorial plane CL, and the performance on snow can be improved.

During cornering on snow, snow mainly enters into the groove component extending in the tire circumferential direction, that is, the first circumferential groove 14, the second circumferential groove 16, the third circumferential groove 18, and the inclined groove 30. Since a snow column shearing force is generated in the tire width direction, cornering performance on snow can be obtained.
Further, the first sub-groove 34 and the second sub-groove 36 formed in the inclined land portion 22 extend in the tire width direction as a whole, but are curved so as to protrude in the tire circumferential direction, Because it has a groove component extending in the tire circumferential direction, it can generate snow column shearing force in the tire width direction compared to the lug groove extending linearly in the tire width direction, and this also cornering performance on snow Can be improved.

  Further, since the sipe that closes at the time of ground contact and the groove that does not close at the time of ground contact are alternately arranged on the center side of the inclined land portion 22 (the sipe 38A-2, the second sub groove 36, the sipe 38B, the first sub land portion 22). Groove 34), as a result of the small land portion between the sipe and the sub-groove falling to the sipe side, when the sipe adjacent to the sub-groove is closed, the sub-groove is opened as much as the sipe is closed. It becomes easy to grab snow on the snow, and this can further improve the performance on snow.

  When considering the elongated land portion, comparing the longitudinal center portion and the longitudinal end portion of the land portion, the rigidity of the land portion is lower at the longitudinal end portion than at the longitudinal center portion. In the pneumatic tire 10 of the present embodiment, as shown in FIG. 2, the first sub-portion closer to the longitudinal end of the inclined land portion 22 than the second sub-groove 36 close to the longitudinal center of the inclined land portion 22. Since the groove width and groove depth of the groove 34 are wide and shallow, the rigidity of the entire inclined land portion 22 is uniform in the longitudinal direction, which is a preferable form. Further, in order to ensure the performance on snow, the snow on the snow must be inserted into the groove. In the present embodiment, the groove width and the groove depth of the first sub groove 34 than the second sub groove 36 are used. Since the groove is formed to be wide and shallow, the groove volume of the second sub-groove 36 and the groove volume of the first sub-groove 34 that are necessary for entering snow on the snow can be made close to each other. This is a preferable form for securing the performance.

  A plurality of sipes (sipe 38A-1, sipe 38A-2, sipe 38B, sipe 38C, and sipe 38D) are formed on the inclined land portion 22 of the present embodiment, and each sipe is convex in the tire circumferential direction. Since the curved convex part of the small land part is fitted to the curved concave part of the adjacent small land part, when the lateral force is input, the convex part and the concave part are recessed. The portions are caught with each other, the deformation of the inclined land portion 22 is suppressed, and the rigidity of the land portion is improved as compared with the case where each sipe is linear.

  Sipe 38A-1 and sipe 38C are formed on both ends in the longitudinal direction of the inclined land portion 22, and these sipes are closed when the inclined land portion 22 contacts the road surface and the sipe wall surfaces are in close contact with each other. The deformation of the inclined land portion 22 at both ends in the longitudinal direction can be suppressed rather than forming a sub-groove that does not close at the time of grounding.

  Furthermore, since each sipe formed in the inclined land portion 22 is curved so as to be convex in the tire circumferential direction, for example, not only the braking performance on the wet road surface and snow where the edge component in the tire width direction works. Further, since the edge component in the tire circumferential direction is also provided, the edge component in the tire circumferential direction can be applied during cornering, and the cornering performance on a wet road surface or on snow can be improved.

  In the pneumatic tire 10 of the present embodiment, the tire width direction center of the inclined groove 30 that defines the inclined land portion 22 is positioned on the outer side in the vehicle width direction when the vehicle is mounted than the tire equatorial plane CL. When the ground contact surface is displaced outward in the vehicle width direction of the tire equator surface CL during cornering, the ratio of the inclined grooves 30 on the ground contact surface increases, so that wet performance during cornering can be improved.

  Since the inclined groove 30 is shallower on the tire equatorial plane CL side where the contact pressure is higher than that on the shoulder side, the rigidity of the land portion in the portion of the inclined land portion 22 where the contact pressure is higher on the tire equatorial plane CL side is improved. Therefore, deformation of the inclined land portion 22 on the tire equatorial plane CL side can be suppressed. Thereby, steering stability can be improved. Further, since the inclined groove 30 has a wider groove width and a deeper groove depth on the first circumferential groove 14 side, the water in the inclined groove 30 is efficiently drained to the first circumferential groove 14. be able to.

Moreover, since the step part 40 is formed in the inclined land part 22 facing the inclined groove 30 on the side where the corner part 24 is formed (arrow A direction side), the drainage performance in the inclined groove 30 is improved. While ensuring, the rigidity of the inclined land portion 22 can be improved and the collapse can be suppressed. In the present embodiment, the stepped portion 40 is formed only on the side of the inclined land portion 22 in the direction of arrow A. However, a stepped portion having the same configuration as that of the stepped portion 40 may be formed on the side opposite to the arrow A direction. .
In addition, although the step part 40 of this embodiment has a rectangular cross-sectional shape, the cross-sectional shape of the step part 40 may be other shapes such as a triangle.

  In the present embodiment, the first protrusion 46 and the second protrusion 58 are provided in each of the first circumferential groove 14, the second circumferential groove 16, and the third circumferential groove 18 that extend along the tire circumferential direction. And the third protrusion 66 is provided, so that the snow column formed by entering these grooves is prevented from shifting in the tire circumferential direction, and traction on the snow compared to the case without these protrusions. Performance and brake performance can be improved.

  Moreover, in this embodiment, since the sound absorption cavity part 52 is comprised in the 2nd land part 50, a higher noise suppression effect can be acquired.

  When the radius of curvature R of the sipe 38A-1, sipe 38A-2, sipe 38B, and sipe 38C formed on the inclined land portion 22 exceeds 50 mm, the edge of the sipe approaches a straight line, and the edge component in the tire circumferential direction As a result, cornering performance cannot be improved.

Further, when the angle θ between the imaginary line FL that linearly connects one end and the other end in the longitudinal direction of the sipe 38A-1, sipe 38A-2, sipe 38B, and sipe 38C and the tire width direction exceeds 30 °, The edge component in the tire width direction which is effective for traction and braking (when traveling straight) is insufficient. Further, if a part of sipe exceeds 45 °, the curvature becomes steep and it becomes difficult to increase the number of sipe, or an extremely thin block can be formed, resulting in poor durability.
Note that the radii of curvature of the first sub-groove 34 and the second sub-groove 36 and the angle of the imaginary line formed with the tire width direction are the same as in the above sipe.

  In the present embodiment, with respect to the groove widths of the first sub-groove 34 and the second sub-groove 36, the tire equatorial plane CL side is widened, and the side opposite to the tire equatorial plane CL (shoulder side) is gradually narrowed. Yes.

  The tire circumferential pitches of the low-angle sipe 59 and the high-angle sipe 64 are determined in consideration of the balance between the reduction in land rigidity (ground pressure) necessary for suppressing uneven wear and the required edge effect. Is.

Here, in the pneumatic tire 10 of the present embodiment, it becomes difficult to prevent uneven wear when the angle of the low-angle sipe 59 with respect to the tire width direction exceeds 15 °.
Further, if the groove depth of the low angle sipe 59 is 20% less than the groove depth of the third circumferential groove 18, the effect of preventing uneven wear is reduced, and the groove depth of the low angle sipe 59 is the third circumference. If it exceeds 50% of the groove depth of the directional groove 18, the shoulder block rigidity is significantly lowered, and the cornering performance and the like are deteriorated.

If the angle of the high angle sipe 64 with respect to the tire width direction is less than 45 °, the edge effect is reduced due to the shortening of the high angle sipe 64, the braking performance is weakened, and the angle of the high angle sipe 64 with respect to the tire width direction is 74 °. If it exceeds, the effect of capturing the road surface of the high-angle sipe 64 is reduced, and the braking performance is weakened.
Further, when the groove depth of the high angle sipe 64 is 20% of the groove depth of the third circumferential groove 18, the edge effect is reduced, the braking performance is weakened, and the groove depth of the high angle sipe 64 is the first. If it exceeds 80% of the groove depth of the three circumferential grooves 18, the shoulder block rigidity is significantly lowered, and the cornering performance and the like are deteriorated.

[Other Embodiments]
In the above-described embodiment, the high-angle sipe 64 is inclined upward to the right, but may be inclined upward.
In the out-side shoulder land portion 70 of the above embodiment, a sipe 75 and a sipe 76 are formed as sipe extending in the tire width direction on the first circumferential groove 14 side, and are formed in the in-side shoulder land portion 60. The high-angle sipe 64 is not formed, but a high-angle sipe may be formed on the out-side shoulder land portion 70 in order to reduce the rigidity of the land portion on the first circumferential groove 14 side.

  In the above-described embodiment, two grooves, the first sub-groove 34 and the second sub-groove 36, are formed in the inclined land portion 22 as grooves that do not close when grounding. However, three or more grooves that do not close when grounding are formed. You may do it. The number of sipes and sub-grooves formed on the inclined land portion 22 may be determined in consideration of the balance between performance on snow and steering stability (land portion rigidity), and the number of each is not limited to that of the above embodiment. .

  The sipe 38A-1, sipe 38A-2, sipe 38B, sipe 38C, first sub-groove 34, and second sub-groove 36 formed in the inclined land portion 22 have a curvature when the tread 12 is viewed in plan view. Although the arc has a single radius R, it may be a convex shape in the circumferential direction, may have a plurality of radii of curvature, or may have a curved shape other than an arc.

The inclined groove 30 of the present embodiment is shallower on the tire equatorial plane CL side where the contact pressure is higher than that on the shoulder portion side. However, the inclined groove 30 has a groove depth from the shoulder portion side toward the tire equatorial plane CL side. It may be gradually shallower.
In the above embodiment, the sipe formed on the inclined land portion 22 and the convex direction of the sub-groove are in the direction of arrow A, but the convex direction may be opposite to the direction of arrow A in some cases.

(Test example)
The wet brake performance was evaluated for one type of pneumatic tire of an example to which the present invention was applied and two types of pneumatic tires of comparative examples.
In each evaluation, the index of Comparative Example 1 was set to 100, and the evaluation was based on an index. Higher values indicate better performance.
For the wet brake performance, the braking distance was measured when full braking was performed from a state where the vehicle traveled at a speed of 80 km / h on a wet road surface with a depth of 2 mm, which is very slippery.
Wet cornering performance was compared by a sensory evaluation of the ease of cornering by running on a test course with a professional test driver on a wet surface wet with water.
The uneven wear resistance performance was evaluated by performing an endurance test by running an actual vehicle, measuring the amount of fall due to uneven wear on the shoulder block, and indexing it compared with the fall amount of Comparative Example 1.

Example tire: The pneumatic tire described in the above embodiment. The groove depth of the low angle sipe is 3 mm, the groove depth of the high angle sipe is 7.1 mm, the angle of the low angle sipe with respect to the tire width direction is 7 °, and the angle of the high angle sipe with respect to the tire width direction is 62 °.
Tire of Comparative Example 1: In the pneumatic tire of the embodiment, all the sipes formed on the side of the third circumferential groove 18 of the sipe 62 extending in the tire circumferential direction of the in-side shoulder land portion 60 are the low-angle sipe 59. Pneumatic tire (the number of sipes is the same as in the example. There is no high-angle sipe 64 inclined with respect to the tire width direction).
Tire of Comparative Example 2: In the pneumatic tire of the embodiment, all the sipes formed on the side of the third circumferential groove 18 of the sipe 62 extending in the tire circumferential direction of the in-side shoulder land portion 60 are set to the high angle sipe 64. Pneumatic tire (the number of sipes is the same as in the example. There is no low-angle sipe 59 extending in the tire width direction).

  From the test results, it can be seen that the pneumatic tires of the examples to which the present invention was applied are excellent in wet brake performance, wet cornering performance, and uneven wear resistance performance.

10 Pneumatic tire 12 Tread 14 First circumferential groove (circumferential groove)
16 Second circumferential groove (circumferential groove)
18 Third circumferential groove (circumferential groove)
59 Low Angle Sipe
64 High Angle Sipe
66 Third protrusion (bottom raised protrusion)

Claims (5)

A land portion extending along the tire circumferential direction defined by the circumferential groove is provided on the innermost side in the vehicle width direction when the tread is mounted on the vehicle,
The land portion has a high-angle sipe extending incline with respect to the tire width direction on the innermost circumferential groove side in the vehicle width direction, and a low angle with a smaller angle with respect to the tire width direction than the high-angle sipe. Angle sipes are formed alternately in the tire circumferential direction ,
The circumferential groove disposed on the innermost side in the vehicle width direction is connected to a side of an acute angle portion of the land portion formed by the circumferential groove and the high-angle sipe, and reinforces the acute angle portion. A pneumatic tire provided with a raised bottom projection . The angle of the low-angle sipe with respect to the tire width direction is set to 15 ° or less,
The groove depth of the low angle sipe is set within a range of 20 to 80% of the groove depth of the circumferential groove,
The angle with respect to the tire width direction of the high angle sipe is set within a range of 45 to 75 °,
The pneumatic tire according to claim 1, wherein a groove depth of the high-angle sipe is set within a range of 20 to 50% of a groove depth of the circumferential groove. The dimension in the tire width direction of the bottom raised protrusion is smaller than the groove width of the circumferential groove,
3. The pneumatic tire according to claim 1 , wherein a shape of the bottom raised protrusion in a tread plan view is an isosceles trapezoid in which an upper bottom is disposed on a groove side and a lower bottom is disposed on an acute angle portion side. The pneumatic tire according to any one of claims 1 to 3, wherein the acute angle portion is formed with a chamfer that is inclined toward an acute angle front end portion. The pneumatic tire according to any one of claims 1 to 4, wherein each of the high-angle sipe and the low-angle sipe opens in a circumferential groove.