JP2022051885A - tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tire improving drainage performance while maintaining steering stability and noise performance.

SOLUTION: An inner middle land part 12 is formed with: multiple first inner middle lateral grooves 41 which extend inward in a tire axial direction from an inner shoulder main groove 6, and each of which has a first inner end 41i in the tire axial direction within the inner middle land part 12; first inner middle lateral sipes 42 connecting the respective first inner ends 41i and an inner crown main groove 4; multiple second inner middle lateral grooves 43 which extend inward in the tire axial direction from the inner shoulder main groove 6, and each of which has a second inner end 43i in the tire axial direction within the inner middle land part 12; and second inner middle lateral sipes 44 which extend inward in the tire axial direction from the respective second inner ends 43i, and each of which has a third inner end 44i in the axial tire direction within the inner middle land part 12. A length of the second inner middle lateral groove 43 in the tire axial direction is equal to or more than 50% of a length of the inner middle land part 12 in the tire axial direction.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a tire having improved drainage performance while maintaining steering stability performance and noise performance.

Conventionally, various tires with improved drainage performance have been proposed (see, for example, Patent Document 1).

However, even in the technique shown in Patent Document 1, it is not easy to achieve both steering stability performance, noise performance and drainage performance at a high level, and further improvement is desired.

Japanese Unexamined Patent Publication No. 2013-100020

The present invention has been devised in view of the above circumstances, and a main object of the present invention is to provide a tire having improved drainage performance while maintaining steering stability performance and noise performance.

The present invention is a tire having a tread portion, and the tread portion is a first tire extending continuously on one side of the tire equatorial line with a first tread ground contact end and the side of the first tread ground contact end in the tire circumferential direction. The shoulder main groove, the first crown main groove extending continuously in the tire circumferential direction between the first shoulder main groove and the tire equatorial line, and between the first shoulder main groove and the first crown main groove. Including the first middle land portion, the first middle land portion extends inward in the tire axial direction from the first shoulder main groove, and the first inner end in the tire axial direction is provided in the first middle land portion. A plurality of first middle lateral grooves, a first middle lateral sipe connecting each first inner end and the first crown main groove, and the first one extending inward in the tire axial direction from the first shoulder main groove. A plurality of second middle lateral grooves having a second inner end in the tire axial direction are formed in the middle land portion, and the tire axial length of the second middle lateral groove is the tire axial length of the first middle lateral groove. 50% or more of.

In the tire according to the present invention, it is desirable that the second middle lateral groove is provided between the first middle lateral grooves adjacent to each other in the tire circumferential direction.

In the tire according to the present invention, it is desirable that the tire axial length of the first middle lateral groove is 50% or more of the tire axial length of the first middle land portion.

In the tire according to the present invention, between the first middle lateral groove and the second middle lateral groove adjacent to each other in the tire circumferential direction, the first shoulder main groove extends inward in the tire axial direction. It is desirable that a third middle lateral sipe having a fourth inner end in the tire axial direction is provided in the middle land portion.

In the tire according to the present invention, it is desirable that the first middle lateral groove and the second middle lateral groove are inclined in the same direction with respect to the tire axial direction.

In the tire according to the present invention, it is desirable that the first middle land portion has a first chamfered portion at a corner portion where the first middle lateral groove intersects the first shoulder main groove at an acute angle.

In the tire according to the present invention, it is desirable that the first middle land portion has a second chamfered portion at a corner portion where the second middle lateral groove intersects the first shoulder main groove at an acute angle.

In the tire according to the present invention, it is desirable that the tire axial length of the second middle lateral sipe is 15% to 35% of the tire axial length of the second middle lateral groove.

In the tire according to the present invention, it is desirable that the tire axial length of the first middle lateral groove is 60% to 80% of the tire axial length of the first middle land portion.

In the tire according to the present invention, the tread portion is provided with a first shoulder land portion between the first tread ground contact end and the first shoulder main groove, and the first shoulder land portion is provided with the first shoulder land portion. A plurality of first shoulder lateral grooves extending inward in the tire axial direction from the first tread ground contact end and having a fifth inner end in the tire axial direction in the first shoulder land portion, each fifth inner end and the first shoulder. It is desirable that a first shoulder tread connecting the main groove is formed.

In the tire according to the present invention, it is desirable that the tire axial length of the first shoulder lateral groove is 50% or more of the tire axial length of the first shoulder land portion.

In the tire according to the present invention, it is desirable that the first shoulder lateral groove extends outward in the tire axial direction of the first tread ground contact end.

In the tire according to the present invention, it is desirable that the angle of the first shoulder lateral groove with respect to the tire axial direction is 5 to 12 °.

In the tire according to the present invention, a plurality of second shoulder lateral sipes connecting the first tread ground contact end and the first shoulder main groove are provided between the first shoulder lateral grooves adjacent to each other in the tire circumferential direction. It is desirable to have.

In the tire according to the present invention, it is desirable that the first tread ground contact end is an inner tread ground contact end located inside the vehicle when mounted on the vehicle.

In the tire of the present invention, the drainage performance of the first middle land portion is improved by the first middle lateral groove and the second middle lateral groove communicating with the first shoulder main groove. In particular, since the tire axial length of the second middle lateral groove is 50% or more of the tire axial length of the first middle land portion, it is possible to easily improve the drainage performance of the first middle land portion. Become. Since the first middle lateral groove and the second middle lateral groove are terminated in the first middle land portion, the noise performance of the tread portion is enhanced, and the rigidity of the first middle horizontal portion is enhanced to improve the steering stability performance.

Further, the first middle horizontal sipe and the second middle horizontal sipe further enhance the drainage performance of the first middle land area. Further, the first middle lateral sipe and the second middle lateral sipe are blocked by the high contact pressure on the tread. This makes it possible to easily improve the drainage performance of the first middle land portion while suppressing the deterioration of the noise performance and the steering stability performance. In particular, the first middle lateral sipe connecting the first middle lateral groove and the first crown main groove easily improves the drainage performance of the first middle land portion. Therefore, the noise performance of the tread portion is easily enhanced, and the rigidity of the first middle land portion is easily enhanced to improve the steering stability performance.

It is a development view of the tread part which shows one Embodiment of the tire of this invention. (A) is a sectional view taken along line AA of FIG. 1, and (b) is a sectional view taken along line BB of FIG. It is an enlarged development view of the middle land part and the shoulder land part on the outside of the vehicle of FIG. It is an enlarged development view of the middle land part and the shoulder land part inside the vehicle of FIG. It is an enlarged development view of the crown land part of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a developed view of the tread portion 2 of the tire of the present embodiment. As shown in FIG. 1, the tire of the present embodiment is suitably used as, for example, a pneumatic tire for a passenger car, but the present invention is not limited thereto.

The tire of the present embodiment has an asymmetric tread pattern in which the direction of mounting on the vehicle is specified. The direction of mounting on the vehicle is displayed, for example, in characters or the like on the sidewall portion (not shown).

The tread portion 2 includes a tread ground contact end TE2 on one side of the tire equator C and a tread ground contact end TE1 on the other side of the tire equator C.

The tread ground contact ends TE1 and TE2 mean the outermost tread ground contact ends in the tire axial direction when a normal load is applied to a tire in a normal state and the tire is grounded on a flat surface at a camber angle of 0 °. Here, the normal state is a state in which the tire is rim-assembled on a normal rim (not shown) and is filled with normal internal pressure without load. Hereinafter, unless otherwise specified, the dimensions and the like of each part of the tire are values measured in this normal state.

A "regular rim" is a rim defined for each tire in the standard system including the standard on which the tire is based. For example, "standard rim" for JATMA, "Design Rim" for TRA, and ETRTO. If so, it is "Measuring Rim".

"Regular internal pressure" is the air pressure defined for each tire in the standard system including the standard on which the tire is based. For JATMA, "maximum air pressure", for TRA, the table "TIRE LOAD LIMITS". The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "INFLATION PRESSURE" for ETRTO. If the tires are for passenger cars, the normal internal pressure is, for example, 180 kPa.

"Regular load" is the load defined for each tire in the standard system including the standard on which the tire is based. If it is JATTA, it is the "maximum load capacity", and if it is TRA, it is the table "TIRE LOAD". The maximum value described in "LIMITS AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO. When the tire is for a passenger car, the normal load is, for example, a load corresponding to 88% of the load.

In the present embodiment, the tread ground contact end TE1 is preferably used as an outer tread ground contact end located on the outside of the vehicle when mounted on the vehicle, but may be used as an inner tread ground contact end located on the inside of the vehicle when mounted on the vehicle. good. Hereinafter, a case where the tread grounding end TE1 is the outer tread grounding end and the tread grounding end TE2 is the inner tread grounding end will be described.

The tread portion 2 has an outer shoulder main groove 5 (second shoulder main groove) extending continuously in the tire circumferential direction on the side of the outer tread ground contact end TE1 (second tread ground contact end), and the outer shoulder main groove 5 and the tire equatorial line. The outer crown main groove 3 (second crown main groove) extending continuously in the tire circumferential direction from C is included. The tread portion 2 has an inner shoulder main groove 6 (first shoulder main groove) extending continuously in the tire circumferential direction on the side of the inner tread ground contact end TE2 (first tread ground contact end), an inner shoulder main groove 6, and a tire equatorial line. It includes an inner crown main groove 4 (first crown main groove) extending continuously in the tire circumferential direction from C.

The widths W1 and W2 of the crown main grooves 3 and 4 and the widths W3 and W4 of the shoulder main grooves 5 and 6 can be variously determined according to the custom. For example, in the passenger car pneumatic tire of the present embodiment, the widths W1, W2, W3 and W4 are preferably 4.0% to 8.5 of the tread contact width TW.

The tread contact width TW is the distance in the tire axial direction between the tread contact ends TE1 and TE2 when a normal load is applied to the tire in a normal state and the tread is grounded on a flat surface at a camber angle of 0 °.

If the widths W1, W2, W3 and W4 are less than 4.0% of the tread ground contact width TW, the drainage performance may be affected. On the other hand, when the widths W1, W2, W3 and W4 exceed 8.5% of the tread ground contact width TW, the rubber volume of the tread portion 2 may decrease, which may affect the wear resistance performance.

FIG. 2 is a sectional view taken along line AA and a sectional view taken along line BB of the tread portion 2 of FIG. As shown in FIG. 2, the depths D1 and D2 of the crown main grooves 3 and 4 and the depths D3 and D4 of the shoulder main grooves 5 and 6 can be variously determined according to the custom. In the case of the passenger car pneumatic tire of the present embodiment, the depths D1, D2, D3 and D4 are preferably 5 to 10 mm.

If the depths D1, D2, D3 and D4 are less than 5 mm, the drainage performance may be affected. On the other hand, when the above D1, D2, D3 and D4 exceed 10 mm, the rigidity of the tread portion 2 is insufficient, which may affect the steering stability performance.

The tread portion 2 has a crown land portion 10 between the outer crown main groove 3 and the inner crown main groove 4. The tread portion 2 has an outer middle land portion 11 (second middle land portion) between the outer crown main groove 3 and the outer shoulder main groove 5. The tread portion 2 has an outer shoulder land portion 13 (second shoulder land portion) between the outer shoulder main groove 5 and the outer tread ground contact end TE1. The tread portion 2 has an inner middle land portion 12 (first middle land portion) between the inner crown main groove 4 and the inner shoulder main groove 6. The tread portion 2 has an inner shoulder land portion 14 (first shoulder land portion) between the inner shoulder main groove 6 and the inner tread ground contact end TE2.

FIG. 3 shows the outer middle land portion 11 and the outer shoulder land portion 13.

The outer shoulder land portion 13 is formed with a plurality of outer shoulder lateral grooves 51, a plurality of first outer shoulder lateral sipes 52, and a plurality of second outer shoulder lateral sipes 53.

The outer shoulder lateral groove 51 extends inward in the tire axial direction from the outer tread ground contact end TE1 and has an inner end 51i in the tire axial direction in the outer shoulder land portion 13. The outer shoulder lateral groove 51 is curved and extends so as to be inclined with respect to the tire axial direction. The outer shoulder lateral groove 51 improves the drainage performance of the outer shoulder land portion 13. Since the outer shoulder lateral groove 51 is terminated in the outer shoulder land portion 13, the noise performance of the tread portion 2 is enhanced, and the rigidity of the outer shoulder land portion 13 is enhanced to improve the steering stability performance.

The first outer shoulder lateral sipe 52 connects the inner end 51i and the outer shoulder main groove 5. The first outer shoulder lateral sipe 52 is connected to the outer shoulder lateral groove 51 and extends in an inclined direction in the same direction as the outer shoulder lateral groove 51 while being curved.

The second outer shoulder lateral sipe 53 extends inward in the tire axial direction from the outer tread ground contact end TE1 and has an inner end 53i outside the inner end 51i in the tire axial direction. The second outer shoulder lateral sipe 53 extends in parallel with the outer shoulder lateral groove 51, that is, at equal intervals in the circumferential direction, while being curved and inclined in the same direction as the outer shoulder lateral groove 51.

The drainage performance of the outer shoulder land portion 13 is further enhanced by the first outer shoulder lateral sipe 52 and the second outer shoulder lateral sipe 53. Further, the first outer shoulder lateral sipe 52 and the second outer shoulder lateral sipe 53 are blocked by the high contact pressure on the tread. This makes it possible to easily improve the drainage performance of the outer shoulder land portion 13 while suppressing the deterioration of the noise performance and the steering stability performance.

In particular, the first outer shoulder lateral sipe 52 connecting the outer shoulder lateral groove 51 and the outer shoulder main groove 5 easily improves the drainage performance of the outer shoulder land portion 13. On the other hand, since the second outer shoulder lateral sipe 53 terminates in the outer shoulder land portion 13, the continuity of the outer shoulder land portion 13 in the tire circumferential direction is maintained. Therefore, the noise performance of the tread portion 2 is easily enhanced, and the rigidity of the outer shoulder land portion 13 is easily enhanced to improve the steering stability performance.

The outer middle land portion 11 is formed with a plurality of outer middle lateral sipes 31 and 32 extending inward in the tire axial direction from the outer shoulder main groove 5. The outer middle lateral sipes 31 and 32 are smoothly connected to the first outer shoulder lateral sipes 52 via the outer shoulder main groove 5. The fact that the outer middle lateral sipe 31, 32 and the first outer shoulder lateral sipe 52 are smoothly connected after passing through the outer shoulder main groove 5 means that at least the outer middle lateral sipe 31, 32 and the first outer shoulder lateral sipe are connected. The sipe 52 is inclined in the same direction with respect to the tire axial direction, and the virtual line extending the first outer shoulder lateral sipe 52 inward in the tire axial direction and the outer middle lateral sipe 31, 32 are outside the tire axial direction. It means that the virtual line extending in the direction overlaps in the outer shoulder main groove 5 or is slightly displaced in the tire circumferential direction. The amount of deviation in the tire circumferential direction is preferably 2 mm or less, for example. The first outer shoulder lateral sipes 52 and the outer middle lateral sipes 31 and 32 smoothly connected through the outer shoulder main groove 5 function as a series of sipes to improve the drainage performance of the outer middle land portion 11 and the outer shoulder land portion 13. Easily enhance.

Further, due to the smoothly connected outer middle lateral sipes 31, 32 and the first outer shoulder lateral sipes 52, the outer middle land portion 11 and the outer shoulder land portion 13 are replaced with the outer middle lateral sipes 31, 32 and the first outer shoulder lateral sipes. Transform along 52 in the same mode. As a result, for example, the transient characteristic at the time of cornering where the center of the tread moves from the outer middle land portion 11 to the outer shoulder land portion 13 is improved, and it becomes possible to obtain good steering stability performance.

The first outer middle lateral sipe 31 connects the outer shoulder main groove 5 and the outer crown main groove 3. By such a first outer middle lateral sipe 31, the outer shoulder main groove 5 and the outer crown main groove 3 communicate with each other, and the drainage performance of the outer middle land portion 11 can be easily improved.

The second outer middle lateral sipe 32 has an inner end 32i within the outer middle land portion 11. The second outer middle lateral sipe 32 that terminates in the outer middle land portion 11 maintains the continuity of the outer middle land portion 11 in the tire circumferential direction. Therefore, the noise performance of the tread portion 2 is easily enhanced, and the rigidity of the outer middle land portion 11 is easily enhanced to improve the steering stability performance.

The first outer middle lateral sipe 31 and the second outer middle lateral sipe 32 are linear or arcuate with a smaller curvature than the outer shoulder lateral groove 51 and extend in parallel. Such a first outer middle lateral sipe 31 and a second outer middle lateral sipe 32 contribute to the improvement of the drainage performance of the outer middle land portion 11.

The second outer shoulder lateral sipe 53 is provided between the outer shoulder lateral grooves 51 adjacent to each other in the tire circumferential direction. As a result, the outer shoulder lateral groove 51 and the second outer shoulder lateral sipe 53 are alternately arranged in the tire circumferential direction, and the drainage performance, noise performance, and steering stability performance are improved in a well-balanced manner.

The tire axial length L1 of the outer shoulder lateral groove 51 is preferably 50% to 75% of the tire axial length L2 of the outer shoulder land portion 13. If the length L1 is less than 50% of the length L2, the drainage performance may be affected. If the length L1 exceeds 75% of the length L2, the noise performance and the steering stability performance may be affected.

It is desirable that the angle β1 of the first outer middle lateral sipe 31 with respect to the tire axial direction is larger than the angle α1 of the outer shoulder lateral groove 51 with respect to the tire axial direction. The angle β1 connects the inner end where the center line of the first outer middle lateral sipe 31 communicates with the outer crown main groove 3 and the outer end where the center line of the first outer middle lateral sipe 31 communicates with the outer shoulder main groove 5. It is defined by the angle between the straight line and the tire axial direction. The angle α1 is defined by the angle formed by the straight line connecting the inner end 51i and the point where the center line of the outer shoulder lateral groove 51 intersects the outer tread ground contact end TE1 and the tire axial direction.

By setting the angle β1 to be larger than the angle α1, good drainage performance can be obtained in the outer middle land portion 11 when traveling straight. In addition, good drainage performance can be obtained at the outer shoulder land portion 13 when cornering.

It is desirable that the angle β2 of the second outer middle lateral sipe 32 with respect to the tire axial direction is larger than the angle α1 of the outer shoulder lateral groove 51 with respect to the tire axial direction. The angle β2 is the angle formed by the straight line connecting the inner end 32i of the second outer middle lateral sipe 32 and the outer end where the center line of the second outer middle lateral sipe 32 communicates with the outer shoulder main groove 5 and the tire axial direction. Defined in.

By setting the angle β2 to be larger than the angle α1, good drainage performance can be obtained in the outer middle land portion 11 when traveling straight. In addition, good drainage performance can be obtained at the outer shoulder land portion 13 when cornering.

The angle α1 of the outer shoulder lateral groove 51 with respect to the tire axial direction is preferably 5 to 12 °. If the angle α1 is less than 5 °, it may affect the drainage performance when going straight. When the angle α1 exceeds 12 °, the rigidity of the outer shoulder land portion 13 in the tire axial direction is lowered, which may affect the steering stability performance.

The angle β1 of the first outer middle lateral sipe 31 with respect to the tire axial direction is preferably 5 to 35 °. If the angle β1 is less than 5 °, it may affect the drainage performance when going straight. When the angle β1 exceeds 35 °, the rigidity of the outer middle land portion 11 in the tire axial direction is lowered, which may affect the steering stability performance.

The angle β2 of the second outer middle lateral sipe 32 with respect to the tire axial direction is preferably 5 to 35 °. If the angle β2 is less than 5 °, it may affect the drainage performance when going straight. When the angle β2 exceeds 35 °, the rigidity of the outer middle land portion 11 in the tire axial direction is lowered, which may affect the steering stability performance.

In this embodiment, the angle β1 and the angle β2 are set to be equal. As a result, the rigidity of the outer middle land portion 11 in the tire circumferential direction is made uniform, and good steering stability performance can be obtained.

It is desirable that the angle α1 of the outer shoulder lateral groove 51 with respect to the tire axial direction and the angle α2 of the second outer shoulder lateral sipe 53 with respect to the tire axial direction are set to be equal. The angle α2 is defined by the angle formed by the straight line connecting the inner end 53i and the point where the center line of the second outer shoulder lateral sipe 53 intersects the outer tread ground contact end TE1 and the tire axial direction. By setting the angle α1 and the angle α2 equally, the rigidity of the outer shoulder land portion 13 in the tire circumferential direction is made uniform, and good steering stability performance can be obtained.

It is desirable that the outer shoulder lateral groove 51 and the second outer shoulder lateral sipe 53 extend outward in the tire axial direction of the outer tread ground contact end TE1. As a result, good drainage performance is maintained even when the ground contact area of the outer shoulder land portion 13 is extended to the outside in the tire axial direction of the outer tread ground contact end TE1 at the time of cornering or the like.

The tire axial length L3 of the second outer shoulder lateral sipe 53 is smaller than the tire axial length L2 of the outer shoulder land portion 13. The length L3 is preferably 30% to 70% of the length L2. If the length L3 is less than 30% of the length L2, the drainage performance may be affected. If the length L3 exceeds 70% of the length L2, the noise performance and the steering stability performance may be affected.

The tire axial length L4 of the second outer middle lateral sipe 32 is preferably 35% to 70% of the tire axial length L5 of the outer middle land portion 11. If the length L4 is less than 35% of the length L5, the drainage performance may be affected. If the length L4 exceeds 70% of the length L5, the noise performance and steering stability performance may be affected.

It is desirable that the groove width W3 of the outer shoulder main groove 5 is smaller than the groove width W1 of the outer crown main groove 3. With such an outer shoulder main groove 5, good noise performance and steering stability performance can be easily obtained. In the present embodiment, the outer shoulder lateral groove 51, the first outer shoulder lateral sipe 52, the second outer shoulder lateral sipe 53, the first outer middle lateral sipe 31, and the second outer middle lateral sipe 32 function organically. As a result, good drainage performance is maintained even in the outer shoulder main groove 5 described above.

It is desirable that the groove width W3 of the outer shoulder main groove 5 is smaller than the groove width W4 of the inner shoulder main groove 6. Further, it is desirable that the groove width W3 of the outer shoulder main groove 5 is smaller than the groove width of the second crown main groove. With such an outer shoulder main groove 5, good noise performance and steering stability performance can be easily obtained, and good drainage performance is maintained, as described above.

It is desirable that the depth of the first outer middle lateral sipe 31 at the inner end in the tire axial direction is larger than the depth of the first outer middle lateral sipe 31 at the outer end of the tire axial direction. The inner and outer ends of the first outer middle lateral sipe 31 in the tire axial direction extend in the tire axial direction at substantially constant depths, respectively. Such a first outer middle lateral sipe 31, in combination with a second outer middle lateral sipe 32 having an inner end 32i, improves the drainage performance and steering stability performance of the outer middle land portion 11 in a well-balanced manner.

It is desirable that the depth of the first outer shoulder lateral sipe 52 at the center in the tire axial direction is larger than the depth of the first outer shoulder lateral sipe 52 at the inner and outer ends of the first outer shoulder lateral sipe 52 in the tire axial direction. The central portion, the inner end, and the outer end of the first outer shoulder lateral sipe 52 in the tire axial direction extend in the tire axial direction at substantially constant depths, respectively. Such a first outer shoulder lateral sipe 52 improves the drainage performance and the steering stability performance of the outer shoulder land portion 13 in a well-balanced manner.

FIG. 4 shows the inner middle land portion 12 and the inner shoulder land portion 14.

A plurality of first inner middle lateral grooves 41 (first middle lateral grooves) and a plurality of second inner middle lateral grooves 43 (second middle lateral grooves) are formed in the inner middle lateral groove 12. The first inner middle lateral groove 41 extends inward in the tire axial direction from the inner shoulder main groove 6, and has a first inner end 41i in the tire axial direction in the inner middle land portion 12. The second inner middle lateral groove 43 extends inward in the tire axial direction from the inner shoulder main groove 6, and has a second inner end 43i in the tire axial direction in the inner middle land portion 12. The drainage performance of the inner middle land portion 12 is improved by the first inner middle lateral groove 41 and the second inner middle lateral groove 43 communicating with the inner shoulder main groove 6.

In particular, the tire axial length of the second inner middle lateral groove 43 is 50% or more of the tire axial length of the inner middle land portion 12. Such a second inner middle lateral groove 43 makes it possible to easily improve the drainage performance of the inner middle land portion 12.

Since the first inner middle lateral groove 41 and the second inner middle lateral groove 43 are terminated in the inner middle land portion 12, the noise performance of the tread portion 2 is enhanced and the rigidity of the inner middle land portion 12 is enhanced for maneuvering. Stability performance is improved.

The first inner middle lateral groove 41 and the second inner middle lateral groove 43 have a linear shape or an arc shape having a smaller curvature than the inner shoulder lateral groove 61 and extend in parallel. Such a first inner middle lateral groove 41 and a second inner middle lateral groove 43 contribute to the improvement of the drainage performance of the inner middle land portion 12.

A plurality of first inner middle lateral sipes 42 (first middle lateral sipes) and a plurality of second inner middle lateral sipes 44 (second middle lateral sipes) are further formed in the inner middle land portion 12. .. The first inner middle lateral sipe 42 connects the first inner end 41i and the inner crown main groove 4. The second inner middle lateral sipe 44 extends inward in the tire axial direction from the second inner end 43i, and has a third inner end 44i in the tire axial direction in the inner middle land portion 12.

The drainage performance of the inner middle land portion 12 is further enhanced by the first inner middle horizontal sipe 42 and the second inner middle horizontal sipe 44. Further, the first inner middle lateral sipe 42 and the second inner middle lateral sipe 44 are blocked by the high ground pressure on the tread. This makes it possible to easily improve the drainage performance of the inner middle land portion 12 while suppressing the deterioration of the noise performance and the steering stability performance.

In particular, the first inner middle lateral sipe 42 connecting the first inner middle lateral groove 41 and the inner crown main groove 4 easily improves the drainage performance of the inner middle land portion 12. On the other hand, the continuity of the inner middle land portion 12 in the tire circumferential direction is maintained by the second inner middle lateral sipe 44 terminating in the inner middle land portion 12. Therefore, the noise performance of the tread portion 2 is easily enhanced, and the rigidity of the inner middle land portion 12 is easily enhanced to improve the steering stability performance.

The second inner middle lateral groove 43 is provided between the first inner middle lateral grooves 41 adjacent to each other in the tire circumferential direction. As a result, the first inner middle lateral groove 41 and the first inner middle lateral sipe 42 and the second inner middle lateral groove 43 and the second inner middle lateral sipe 44 are alternately arranged in the tire circumferential direction, and the drainage performance, noise performance and maneuvering are performed. Stability performance is improved in a well-balanced manner.

The first inner middle lateral sipe 42 and the second inner middle lateral sipe 44 have a linear shape or an arc shape having a smaller curvature than the inner shoulder lateral groove 61 and extend in parallel. Such a first inner middle horizontal sipe 42 and a second inner middle horizontal sipe 44 contribute to the improvement of the drainage performance of the inner middle land portion 12.

The tire axial length L8 of the first inner middle lateral groove 41 is preferably 50% or more of the tire axial length L7 of the inner middle land portion 12. Such a first inner middle lateral groove 41 makes it possible to easily improve the drainage performance of the inner middle land portion 12.

It is desirable that a third inner middle lateral sipe 45 (third middle lateral sipe) is provided between the first inner middle lateral groove 41 and the second inner middle lateral groove 43 adjacent to each other in the tire circumferential direction. The third inner middle lateral sipe 45 extends inward in the tire axial direction from the inner shoulder main groove 6 and has a fourth inner end 45i in the tire axial direction in the inner middle land portion 12. By providing the third inner middle horizontal sipe 45 on the inner middle land portion 12, it is possible to further improve the drainage performance of the inner middle land portion 12.

It is desirable that the first inner middle lateral groove 41 and the second inner middle lateral groove 43 are inclined in the same direction with respect to the tire axial direction. The first inner middle lateral groove 41 and the second inner middle lateral groove 43 inclined in the same direction make it possible to easily improve the drainage performance of the inner middle land portion 12.

It is desirable that a first chamfered portion 46 is provided at a corner portion where the first inner middle lateral groove 41 intersects the inner shoulder main groove 6 at an acute angle. The first chamfered portion 46 promotes the flow of water flowing from the first inner middle lateral groove 41 into the inner shoulder main groove 6, and makes it possible to easily improve the drainage performance of the inner middle land portion 12. Further, the stress at the corner portion is relaxed by the first chamfered portion 46.

It is desirable that a second chamfered portion 47 is provided at a corner portion where the second inner middle lateral groove 43 intersects the inner shoulder main groove 6 at an acute angle. The second chamfered portion 47 promotes the flow of water flowing from the second inner middle lateral groove 43 into the inner shoulder main groove 6, and makes it possible to easily improve the drainage performance of the inner middle land portion 12. Further, the stress at the corner portion is relaxed by the second chamfered portion 47.

The tire axial length L9 of the second inner middle lateral sipe 44 is preferably 15% to 35% of the tire axial length L6 of the second inner middle lateral groove 43. If the length L9 is less than 15% of the length L6, the drainage performance may be affected. If the length L9 exceeds 35% of the length L6, the noise performance and steering stability performance may be affected.

The tire axial length L8 of the first inner middle lateral groove 41 is preferably 60% to 80% of the tire axial length L7 of the inner middle land portion 12. If the length L8 is less than 60% of the length L7, the drainage performance may be affected. If the length L8 exceeds 80% of the length L7, the noise performance and the steering stability performance may be affected.

In the present embodiment, the inner shoulder land portion 14 is formed with a plurality of inner shoulder lateral grooves 61 (first shoulder lateral groove) and a plurality of first inner shoulder lateral sipes 62 (first shoulder lateral sipes).

The inner shoulder lateral groove 61 extends inward in the tire axial direction from the inner tread ground contact end TE2, and has a fifth inner end 61i in the tire axial direction in the inner shoulder land portion 14. The inner shoulder lateral groove 61 is curved and extends so as to be inclined with respect to the tire axial direction. The inner shoulder lateral groove 61 improves the drainage performance of the inner shoulder land portion 14. Since the inner shoulder lateral groove 61 is terminated in the inner shoulder land portion 14, the noise performance of the tread portion 2 is enhanced, and the rigidity of the inner shoulder land portion 14 is enhanced to improve the steering stability performance.

The first inner shoulder lateral sipe 62 connects the fifth inner end 61i and the inner shoulder main groove 6. The first inner shoulder lateral sipe 62 is connected to the inner shoulder lateral groove 61 and extends in an inclined direction in the same direction as the inner shoulder lateral groove 61 while being curved.

The first inner shoulder lateral sipe 62 connecting the inner shoulder lateral groove 61 and the inner shoulder main groove 6 further enhances the drainage performance of the inner shoulder land portion 14. Further, the first inner shoulder lateral sipe 62 is blocked by a high contact pressure on the tread surface. This makes it possible to easily improve the drainage performance of the inner shoulder land portion 14 while suppressing deterioration of noise performance and steering stability performance.

The tire axial length L10 of the inner shoulder lateral groove 61 is preferably 50% or more of the tire axial length L11 of the inner shoulder land portion 14. With such an inner shoulder lateral groove 61, good drainage performance can be easily obtained.

It is desirable that the inner shoulder lateral groove 61 extends outward in the tire axial direction of the inner tread ground contact end TE2. As a result, good drainage performance is maintained even when the ground contact area of the inner shoulder land portion 14 is extended to the outside in the tire axial direction of the inner tread ground contact end TE2 at the time of cornering or the like.

The angle γ1 of the inner shoulder lateral groove 61 with respect to the tire axial direction is preferably 5 to 12 °. The angle γ1 is defined by the angle formed by the straight line connecting the fifth inner end 61i and the point where the center line of the inner shoulder lateral groove 61 intersects the inner tread ground contact end TE2 and the tire axial direction. If the angle α1 is less than 5 °, it may affect the drainage performance when going straight. When the angle α1 exceeds 12 °, the rigidity of the inner shoulder land portion 14 in the tire axial direction is lowered, which may affect the steering stability performance.

A plurality of second inner shoulder lateral sipes 63 (second shoulder lateral sipes) are formed on the inner shoulder land portion 14 of the present embodiment. The second inner shoulder lateral sipe 63 connects the inner tread ground contact end TE2 and the inner shoulder main groove 6. The drainage performance of the outer shoulder land portion 13 is further enhanced by the second inner shoulder lateral sipe 63. Further, the second inner shoulder lateral sipe 63 is blocked by a high contact pressure on the tread surface. This makes it possible to easily improve the drainage performance of the outer shoulder land portion 13 while suppressing the deterioration of the noise performance and the steering stability performance.

The second inner shoulder lateral sipe 63 is provided between the inner shoulder lateral grooves 61 adjacent to each other in the tire circumferential direction. As a result, the inner shoulder lateral groove 61 and the second inner shoulder lateral sipe 63 are alternately arranged in the tire circumferential direction, and the drainage performance, the noise performance, and the steering stability performance are improved in a well-balanced manner.

It is desirable that the depth of the first inner middle lateral sipe 42 at the center in the tire axial direction is larger than the depth of the first inner middle lateral sipe 42 at the inner and outer ends of the first inner middle lateral sipe 42 in the tire axial direction. Such a first inner middle lateral sipe 42, in combination with a second inner middle lateral sipe 44 having a third inner end 44i, improves the drainage performance and steering stability performance of the inner middle land portion 12 in a well-balanced manner.

It is desirable that the depth of the first inner shoulder lateral sipe 62 at the center in the tire axial direction is larger than the depth of the first inner shoulder lateral sipe 62 at the inner and outer ends of the first inner shoulder lateral sipe 62 in the tire axial direction. The central portion, the inner end, and the outer end of the first inner shoulder lateral sipe 62 in the tire axial direction extend in the tire axial direction at substantially constant depths, respectively. Such a first inner shoulder lateral sipe 62 improves the drainage performance and steering stability performance of the inner shoulder land portion 14 in a well-balanced manner.

FIG. 5 shows the crown land portion 10. A crown lateral sipe 21 and a crown lateral groove 22 are formed on the crown land portion 10. The crown lateral sipe 21 extends inward in the tire axial direction from the outer crown main groove 3 and has an inner end in front of the tire equator C. The crown lateral sipe 21 is inclined in the direction opposite to that of the first outer middle lateral sipe 31. The crown lateral groove 22 extends inward in the tire axial direction from the inner crown main groove 4, and has an inner end in front of the tire equator C. The crown lateral groove 22 is inclined in the direction opposite to that of the first inner middle lateral groove 41. The crown lateral sipe 21 and the crown lateral groove 22 are inclined in the same direction with respect to the tire axial direction and extend in parallel with each other.

In the crown land portion 10, the crown lateral sipe 21 is arranged on the side of the outer tread grounding end TE1 and the crown lateral groove 22 is arranged on the side of the inner tread grounding end TE2, so that the crown land portion is arranged on the side of the outer tread grounding end TE1. The rigidity of the crown 10 is easily increased, and the drainage performance of the crown land portion 10 is easily increased on the side of the inner tread ground contact end TE2. Therefore, by using the outer tread ground contact end TE1 as the outer tread ground contact end, it is possible to easily improve the drainage performance while maintaining the steering stability performance and the noise performance.

It is desirable that a third chamfered portion 23 is provided at a corner portion where the crown lateral groove 22 intersects the inner crown main groove 4 at an acute angle. The third chamfered portion 23 promotes the flow of water flowing from the crown lateral groove 22 into the inner crown main groove 4, and makes it possible to easily improve the drainage performance of the crown land portion 10. Further, the stress of the corner portion is relaxed by the third chamfer portion 23.

Although the tire of the present invention has been described in detail above, the present invention is not limited to the above-mentioned specific embodiment, but is modified to various embodiments.

A size 215 / 60R16 pneumatic tire with the basic tread pattern of FIG. 1 was prototyped based on the specifications in Table 1 and tested for drainage performance, noise performance and steering stability performance. Comparative Example 1 is a pneumatic tire having a tread pattern disclosed in Patent Document 1. The test method is as follows.

<Drainage performance>
The test tires mounted on the rim 16 × 7.0J were mounted on all wheels of a passenger FF vehicle with a displacement of 2500cc under the condition of an internal pressure of 250kPa. The above vehicle was brought to a test course on an asphalt road surface with a depth of 5 mm and a length of 20 m and a radius of 100 m, the lateral acceleration (lateral G) of the front wheels during running was measured, and the speed of the test vehicle was increased. The average lateral G at 50-80 km / h was calculated (lateral hydroplaning test). The results are shown by an index with Example 1 as 100. The higher the number, the better.

<Noise performance>
In the above test vehicle, the noise inside the vehicle when traveling on a road noise measurement road (rough asphalt road) at a speed of 60 km / h was collected by a microphone installed at the driver's seat window side ear clearance position, and the sound pressure level was measured. rice field. The result is shown by an index with the value of Example 1 as 100, and the larger the value, the better.

<Maneuvering stability performance>
The test vehicle ran on a dry asphalt road surface test course with one driver, and the characteristics related to grip performance, steering response, and responsiveness were evaluated by the driver's sensuality. The result is a score with Example 1 as 100, and the larger the value, the better the steering stability performance.

As is clear from Table 1, it was confirmed that the tires of the examples were significantly improved in drainage performance, noise performance and steering stability performance in a well-balanced manner as compared with the comparative examples.

2: Tread portion 4: 1st crown main groove 6: 2nd shoulder main groove 12: 1st middle land portion 14: 1st shoulder land portion 41: 1st middle lateral groove 41i: 1st inner end 42: 1st middle lateral Sipe 43: 2nd middle lateral groove 43i: 2nd inner end 44: 2nd middle lateral sipe 44i: 3rd inner end 45: 3rd middle lateral sipe 45i: 4th inner end 46: 1st chamfer 47: 2nd chamfer Part 61: 1st shoulder lateral groove 61i: 5th inner end 62: 1st shoulder lateral sipe 63: 2nd shoulder lateral sipe C: Tire equatorial line TE1: 2nd tread ground contact end TE2: 1st tread ground contact end

Claims (16)

A tire with a tread
The tread portion is
The first tread ground contact end on one side of the tire equator,
The first shoulder main groove that extends continuously in the tire circumferential direction on the side of the first tread ground contact end,
A first crown main groove extending continuously in the tire circumferential direction between the first shoulder main groove and the tire equator,
Includes a first middle land portion between the first shoulder main groove and the first crown main groove.
In the first middle land area,
A plurality of first middle lateral grooves extending inward in the tire axial direction from the first shoulder main groove and having a first inner end in the tire axial direction in the first middle land portion.
A first middle lateral sipe connecting each first inner end and the first crown main groove,
A plurality of second middle lateral grooves extending inward in the tire axial direction from the first shoulder main groove and having a second inner end in the tire axial direction are formed in the first middle land portion.
The tire axial length of the second middle lateral groove is 50% or more of the tire axial length of the first middle land portion.
tire. The tread portion extends inward in the tire axial direction from each second inner end, and a second middle lateral sipe having a third inner end in the tire axial direction is formed in the first middle land portion.
The tire according to claim 1, wherein the first middle horizontal sipe and the second middle horizontal sipe extend in parallel. The tire according to claim 1 or 2, wherein the second middle lateral groove is provided between the first middle lateral grooves adjacent to each other in the tire circumferential direction. The tire according to any one of claims 1 to 3, wherein the tire axial length of the first middle lateral groove is 50% or more of the tire axial length of the first middle land portion. Between the first middle lateral groove and the second middle lateral groove adjacent to each other in the tire circumferential direction, the first shoulder main groove extends inward in the tire axial direction, and the tire axial direction is formed in the first middle land portion. The tire according to any one of claims 1 to 4, wherein a third middle lateral sipe having a fourth inner end is provided. The tire according to any one of claims 1 to 5, wherein the first middle lateral groove and the second middle lateral groove are inclined in the same direction with respect to the tire axial direction. The tire according to claim 6, wherein the first middle land portion has a first chamfered portion at a corner portion where the first middle lateral groove intersects the first shoulder main groove at an acute angle. The tire according to claim 6 or 7, wherein the first middle land portion has a second chamfered portion at a corner portion where the second middle lateral groove intersects the first shoulder main groove at an acute angle. The tire according to any one of claims 1 to 8, wherein the tire axial length of the second middle lateral sipe is 15% to 35% of the tire axial length of the second middle lateral groove. The tire according to any one of claims 1 to 9, wherein the tire axial length of the first middle lateral groove is 60% to 80% of the tire axial length of the first middle land portion. The tread portion is provided with a first shoulder land portion between the first tread ground contact end and the first shoulder main groove.
On the land of the first shoulder,
A plurality of first shoulder lateral grooves extending inward in the tire axial direction from the first tread ground contact end and having a fifth inner end in the tire axial direction in the first shoulder land portion.
The tire according to any one of claims 1 to 10, wherein a first shoulder lateral sipe connecting each fifth inner end and the first shoulder main groove is formed. The tire according to claim 11, wherein the tire axial length of the first shoulder lateral groove is 50% or more of the tire axial length of the first shoulder land portion. The tire according to claim 11 or 12, wherein the first shoulder lateral groove extends outward in the tire axial direction of the first tread ground contact end. The tire according to any one of claims 11 to 13, wherein the angle of the first shoulder lateral groove with respect to the tire axial direction is 5 to 12 °. Claims 11 to 14 are provided with a plurality of second shoulder lateral sipes connecting the first tread ground contact end and the first shoulder main groove between the first shoulder lateral grooves adjacent to each other in the tire circumferential direction. Tires listed in any of. The tire according to any one of claims 1 to 15, wherein the first tread ground contact end is an inner tread ground contact end located inside the vehicle when the vehicle is mounted.

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