JP5419752B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can be used for all seasons.

  All-season tires are required to balance the performance on snow with dry and wet running performance at a high level.

  As a tread pattern of a conventional all-season tire, for example, a tread pattern as described in Patent Document 1 is representative.

Japanese Patent No. 3229953

  In a configuration like the current pattern, in order to ensure on-snow performance, a lug groove having a relatively large angle with respect to the circumferential direction is inserted, and the number of narrow grooves equally placed in the block is increased. Although this method aims to ensure performance, attempts to improve on-snow performance with this method will lead to a decrease in block rigidity and a decrease in dry and wet handling performance. Moreover, since the angle of the lug groove is close to the tire width direction, it is disadvantageous for drainage performance.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire that can improve performance on snow while ensuring dry performance and wet performance.

  This invention is made | formed in view of the said fact, Comprising: The pneumatic tire of Claim 1 is provided in the said tread, The several circumferential groove | channel extended along a tire circumferential direction, and a tire width direction An outermost circumferential groove disposed on one outermost side of the tire, a land portion formed between the outermost circumferential groove and a second circumferential groove adjacent to the outermost circumferential groove, and a tire from the outermost circumferential groove. A plurality of lug grooves that extend toward the equator plane and that are inclined with respect to the tire equatorial plane and arranged at intervals in the tire circumferential direction, and the land portion extends in the tire circumferential direction by the lug grooves. On the side where the corner on the outermost circumferential groove side of the partitioned land section is an acute angle, it faces the lug groove and rises from the groove bottom of the lug groove and is lower than the tread surface of the partitioned land section A step portion having a step surface is directed from the outermost circumferential groove toward the tire equator side. That it is formed Te, and is characterized in.

  Next, the operation of the pneumatic tire according to claim 1 will be described.

  First, since a plurality of circumferential grooves extending along the tire circumferential direction are arranged on the tread, basic drainage properties, straight running stability during dry and wet traveling are ensured.

  Further, by disposing a plurality of lug grooves inclined with respect to the tire equatorial plane from the outermost circumferential groove toward the tire equatorial plane side, higher drainage performance than the studless tire can be exhibited. Furthermore, noise can be suppressed.

  When the lug groove is inclined with respect to the tire equatorial plane, one corner in the tire circumferential direction becomes an acute angle and the other side becomes an obtuse angle. The side where the corner portion of the demarcation land portion becomes an acute angle has low rigidity and tends to fall down due to the addition of a load.

  In this invention, the level | step-difference part is formed toward the tire equatorial plane side from the outermost circumferential direction groove | channel on the side in which the corner | angular part by the side of the outermost circumferential direction groove | channel side of a division land part becomes an acute angle. The step portion faces the lug groove, and the step portion rises from the bottom of the lug groove and has a step surface lower than the outermost surface in the tire radial direction of the land section. By configuring such a stepped portion, it is possible to improve the rigidity of the demarcated land portion and suppress the collapse while ensuring the drainage performance in the lug groove.

  The invention according to claim 2 is characterized in that the angle of the lug groove with respect to the tire equatorial plane is inclined at 20 ° to 60 °.

  If the angle of the lug groove with respect to the tire circumferential direction is less than 20 °, the section land portion becomes longer in the tire circumferential direction, and there is a concern that the motion performance is deteriorated. On the other hand, when the angle of the lug groove with respect to the tire circumferential direction exceeds 60 °, there is no merit for drainage performance. Therefore, the lug groove is preferably inclined within the range of 20 ° to 60 ° with respect to the tire circumferential direction.

  The invention according to claim 3 is characterized in that the protruding width of the stepped portion to the lug groove is 10% to 15% of the average groove width of the lug groove.

  If the protruding width of the stepped portion to the lug groove is less than 10%, there is no merit for the rigidity of the land section. Moreover, if it exceeds 50%, the merit with respect to the drainage performance in a lug groove will be lost. Therefore, it is preferable that the protruding width of the stepped portion to the lug groove is 10% to 50% of the average groove width of the lug groove.

  The invention according to claim 4 is characterized in that the height of the step portion from the groove bottom of the lug groove is 30% to 70% of the depth of the lug groove on the outermost circumferential groove side. And

  If the height of the lug groove from the groove bottom is less than 30% of the depth on the outermost circumferential groove side of the lug groove, the fall of the land section cannot be effectively suppressed. Further, if it exceeds 70% of the depth on the outermost circumferential groove side of the lug groove, there is no merit for drainage performance in the lug groove. Therefore, the height of the stepped portion from the groove bottom of the lug groove is preferably 30% to 70% of the depth of the lug groove on the outermost circumferential groove side.

  According to a fifth aspect of the present invention, the lug groove is configured to communicate with the second circumferential groove, and the second circumferential groove side is a shallow groove shallower than the outermost circumferential groove side. It is characterized by that.

  Since the contact pressure of the tread tire near the equator surface is higher than the shoulder side, it is possible to effectively increase the strength of the land section by shallowing the lug groove, and to ensure steering stability Can do.

  The groove bottom of the shallow groove may be flush with the step surface of the step portion or may be lower than the step surface of the step portion.

  According to a sixth aspect of the present invention, three of the circumferential grooves are formed in the tread, and one of the circumferential grooves is disposed on one side with respect to the tire equatorial plane and the outermost circumferential groove. The other two are arranged on the other side with respect to the tire equatorial plane.

  By disposing the circumferential groove as described above, the land portion constituted by the lug groove is disposed on the tire equator surface having a high contact pressure, so that the performance on snow can be improved.

The invention according to claim 7 is characterized in that the lug groove is curved in a direction in which an inclination angle with respect to the tire equatorial plane gradually increases toward the outermost circumferential groove.
According to the said structure, the drainage from the lug groove toward the outermost circumferential groove can be enhanced.

  The invention described in claim 8 is characterized in that the lug groove is curved in a direction in which the angle of the corner on the acute angle side facing the outermost circumferential groove is increased.

  According to the said structure, compared with the case where a lug groove is made into linear form, the distance toward a outermost circumferential groove | channel from a lug groove can be shortened, and drainage property can be improved.

  The invention according to claim 9 is characterized in that a shallow groove shallower than the outermost circumferential groove side, which communicates between the lug grooves adjacent in the tire circumferential direction, is formed in the partition land portion. Features.

  The lug groove with a relatively small inclination angle with respect to the tire circumferential direction is advantageous for drainage performance, but it is disadvantageous for running on snow, but it can run on snow by forming the shallow groove on the land. The disadvantageous part of the time can be compensated, and cornering performance, braking performance, and traction performance on snow can be improved.

  The invention according to claim 10 includes a second land portion configured between the second circumferential groove and the circumferential groove on the opposite side to the outermost circumferential groove, and the second land A plurality of sound absorbing parts each having a resonance cavity part and a communication groove communicating with the resonance cavity part and the second circumferential groove are formed in the tire circumferential direction. .

  As the sound absorbing part, by setting the volume of the resonance cavity part and the cross-sectional area and length of the communication groove based on, for example, the Helmholtz resonance theory, noise at a predetermined frequency can be reduced.

  As described above, since the pneumatic tire according to claim 1 has the above-described configuration, it has an excellent effect that the performance on snow can be improved while ensuring the dry performance and the wet performance.

  Since the pneumatic tire according to claim 2 has the above-described configuration, it is possible to achieve both exercise performance and drainage performance.

  Since the pneumatic tire according to claim 3 has the above-described configuration, it has an excellent effect that the fall of the land section can be effectively suppressed while ensuring the drainage performance in the lug groove.

  Since the pneumatic tire according to claim 4 has the above-described configuration, it has an excellent effect that the fall of the land section can be effectively suppressed while ensuring the drainage performance in the lug groove.

  Since the pneumatic tire according to claim 5 has the above-described configuration, it has an excellent effect that the strength of the land section can be effectively increased.

  Since the pneumatic tire according to claim 6 has the above-described configuration, it has an excellent effect that the performance on snow can be improved.

  Since the pneumatic tire according to claim 7 has the above-described configuration, it has an excellent effect that drainage performance from the lug groove toward the outermost circumferential groove can be improved.

  Since the pneumatic tire according to claim 8 has the above-described configuration, it has an excellent effect that the distance from the lug groove toward the outermost circumferential groove can be shortened and drainage can be improved.

  Since the pneumatic tire according to claim 9 has the above-described configuration, it has an excellent effect that the disadvantageous part at the time of running on snow can be compensated, and cornering performance, braking performance, and traction performance on snow can be improved. Have.

  Since the pneumatic tire according to claim 10 has the above-described configuration, it has an excellent effect that noise during traveling can be reduced.

It is a top view of the tread of the pneumatic tire concerning this embodiment. It is a partial enlarged plan view of the tread of the pneumatic tire concerning this embodiment. It is a partial expansion perspective view of the tread of the pneumatic tire concerning this embodiment. It is a partial expansion perspective view of the tread of the pneumatic tire concerning this embodiment. It is sectional drawing of the lug groove of the pneumatic tire which concerns on this embodiment. It is sectional drawing of the 1st circumferential direction groove | channel of the pneumatic tire which concerns on this embodiment. It is a partial enlarged plan view of the tread of the pneumatic tire concerning this embodiment. It is sectional drawing of the 2nd circumferential groove | channel of the pneumatic tire which concerns on this embodiment. It is a partial expansion perspective view of the tread of the pneumatic tire concerning this embodiment. It is sectional drawing of the 3rd circumferential groove | channel of the pneumatic tire which concerns on this embodiment. It is a top view of the tread of the pneumatic tire concerning the modification of this embodiment.

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). 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 an asymmetric pattern shape with the tire equatorial plane CL in between. The left side of the drawing is the inside when the vehicle is mounted (indicated by an arrow IN), and the right side of the drawing is the vehicle when mounted. It is preferable to be mounted so as to be outside (indicated by an arrow OUT). Further, it is preferable that the tire rotation direction is mounted so that the tire rotation direction is the direction indicated by the arrow R (the lower side in the figure is the stepping side and the upper side is the kicking side). In addition, it is not always necessary to mount with the above-described directionality, and the IN-OUT of the embodiment may be mounted reversely, or the front-rear direction may be mounted reversely.

  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 arranged on one side of the tire equator plane CL (outside when the vehicle is mounted), and the second circumferential groove 16 and the third circumferential groove 18 are on the other side of the tire equator plane CL (vehicle It is arranged on the inner side at the time of wearing. 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 is the outermost circumferential groove on the IN side.

  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 lug grooves 30 are formed in the circumferential direction so as to cross the first circumferential groove 14 and the second circumferential groove 16. The lug groove 30 extends from the first circumferential groove 14 toward the second circumferential groove 16 so as to incline to the left so that the inclination angle with respect to the tire equatorial plane gradually increases.

As shown in FIG. 3, the lug groove 30 has a shallow groove 30 </ b> A having a shallower groove bottom on the second circumferential groove 16 side than on the first circumferential groove 14 side. In the present embodiment, the shallow groove 30A is disposed closer to the second circumferential groove 16 than the tire equatorial plane CL.
Note that the shallow groove 30 </ b> A is not an essential configuration, and the lug groove 30 may be configured to have the same depth over the second circumferential groove 16. Further, the lug groove 30 may have a length up to an intermediate portion in the tire width direction of the partition land portion 22 without being communicated with the second circumferential groove 16.
The lug groove 30 is configured such that the groove width gradually increases from the first circumferential groove 14 side toward the second circumferential groove 16 side. The lug groove 30 has a curved shape in which the upper left side (the kicking side) in the figure slightly bulges.

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

  A land section 22 is formed between adjacent lug grooves 30. The corner 24 on the tire circumferential direction kicking side (upper side in the figure) of the section land portion 22 is an acute angle than the corner 26 on the stepping side (lower side in the figure).

  As shown in FIG. 2, a stepped portion 40 is formed on the corner portion 24 side of the land section 22 so as to face the lug groove 30. As shown in FIG. 5, the step portion 40 has a step surface 42 that rises from the bottom of the lug groove 30 and has a step that is lower than the outermost surface in the tire radial direction of the land section 22. The stepped portion 40 is formed from the end portion of the partition land portion 22 on the first circumferential groove 14 side to the shallow groove 30A.

  The overhanging width W <b> 1 of the stepped portion 40 to the lug groove 30 is preferably 10% to 50% of the average groove width of the lug groove 30. When the projecting width of the stepped portion 40 to the lug groove 30 is less than 10%, there is no merit for the rigidity of the land section 22. Moreover, if it exceeds 50%, the merit with respect to the drainage performance in the lug groove 30 is lost. Therefore, the protruding width of the stepped portion 40 to the lug groove 30 is preferably 10% to 50% of the average groove width of the lug groove 30.

  The height H1 of the stepped portion 40 from the bottom of the lug groove 30 is preferably 30% to 70% of the depth H0 of the lug groove 30 on the first circumferential groove 14 side. If the height of the lug groove 30 from the groove bottom is less than 30% of the depth of the lug groove 30 on the first circumferential groove 14 side, the fall of the section land portion 22 cannot be effectively suppressed. If the depth of the lug groove 30 on the first circumferential groove 14 side exceeds 70%, the merit for drainage performance in the lug groove 30 is lost. Therefore, the height H1 of the step portion 40 from the bottom of the lug groove 30 is preferably 30% to 70% of the depth H0 of the lug groove 30 on the first circumferential groove 14 side.

  In the present embodiment, as shown in FIG. 3, the step surface 42 of the step portion 40 and the groove bottom of the shallow groove 30A are flush with each other.

  The partition land portion 22 includes partition shallow grooves 34 and 36 that connect adjacent lug grooves 30. The partition shallow grooves 34 and 36 are formed in an arc shape that is convex in the kicking-out direction, and are disposed substantially parallel to each other. The partition shallow grooves 34 and 36 are shallower than the depth of the lug groove 30 on the first circumferential groove 14 side, and the groove bottom is flush with the step surface 42.

  The partition land portion 22 is partitioned into a first block 22A, a second block 22B, and a third block 22C sequentially from the IN side by the partition shallow grooves 34 and 36. The first block 22A includes two sipes 38A-1 and 38A-2, the second block 22B includes one sipe 38B, and the third block 22C includes one sipe 38C. Has been. The sipes 38A-1, 38A-2, 38B, and 38C are formed in an arc shape that is substantially parallel to the section shallow grooves 34 and 36 and is convex in the kick-out direction in the same manner as the section shallow grooves 34 and 36.

  The sipe 38 </ b> A- 1 is disposed so as to connect the second circumferential groove 16 and the lug groove 30. Sipe 38A-2, 38B is arrange | positioned so that between the adjacent lug grooves 30 may be connected. The sipe 38C is arranged so as to connect the lug groove 30 and the first circumferential groove 14.

  The acute angle portions 35 and 37 formed between the partition shallow grooves 34 and 36 and the lug groove 30 are chamfered. Further, the acute angle portion 39 formed between the lug groove 30 and the second circumferential groove 16 is also chamfered.

  A first protrusion 46 that protrudes into the first circumferential groove 14 is formed on the corner 24 side of the partition land portion 22. As shown in FIG. 4, the first protrusion 46 has an inclined surface 48 that is inclined from the height of the step surface 42 toward the groove bottom of the first circumferential groove 14. The inclined surface 48 is formed so that the kick-out side is extended from the step surface 42, and the step-on side is formed so that the wall surface on the first circumferential groove 14 side of the partition land portion 22 protrudes. As shown in FIG. 6, the first protrusion 46 has a triangular shape as viewed from the tire circumferential direction.

  The height H2 from the groove bottom on the wall surface side of the land section 22 of the first protrusion 46 is preferably 30% to 70% of the groove depth H5 of the first circumferential groove 14. If the height H2 of the first protrusion 46 is less than 30% of the groove depth H5 of the first circumferential groove 14, the performance on snow cannot be improved effectively. Moreover, if it exceeds 70% of the groove depth H5 of the 1st circumferential direction groove | channel 14, drainage performance and snow performance cannot be made compatible efficiently. Therefore, it is preferable that the height H2 from the groove bottom of the first land 46 on the side of the land section 22 is 30% to 70% of the groove depth H5 of the first circumferential groove 14.

  The overhang width W2 of the first protrusion 46 to the first circumferential groove 14 is preferably 10% to 50% of the groove width W5 of the first circumferential groove 14. If the overhanging width W2 of the first protrusion 46 is less than 10% of the groove width W5 of the first circumferential groove 14, the performance on snow cannot be effectively improved. Further, if it exceeds 50% of the groove width W5 of the first circumferential groove 14, the drainage performance and the on-snow performance cannot be achieved efficiently. Therefore, the overhang width W2 of the first protrusion 46 to the first circumferential groove 14 is preferably 10% to 50% of the groove width W5 of the first circumferential groove 14.

  A second land portion 50 is configured between the second circumferential groove 16 and the third circumferential groove 18. The second land portion 50 is narrower in the tire width direction than the land portion 20. A sound absorbing cavity 52 is formed at the center of the second land portion 50 in the tire width direction. The sound absorbing cavity 52 is a long groove along the tire circumferential direction. The sound absorbing cavity 52 communicates with the sound absorbing shallow groove 54. The sound absorbing shallow groove 54 has one end connected to the stepped side end of the sound absorbing cavity 52 and the other end connected to the second circumferential groove 16. The sound absorbing shallow groove 54 is inclined with respect to the tire equatorial plane CL so that the second circumferential groove 16 side is disposed on the kicking side.

  A sipe 56 is formed on the opposite side of the sound absorbing shallow groove 54 across the sound absorbing cavity 52 of the second land portion 50. The sipe 56 is configured so that one end thereof communicates with the third circumferential groove 18 and the other end reaches the vicinity of the kicking side end of the sound absorbing cavity 52. The sipe 56 is inclined with respect to the tire equatorial plane CL in the same direction as the sound absorbing shallow groove 54 so that the third circumferential groove 18 side is disposed on the stepping side. The sipe 56 is not in communication with the sound absorbing cavity 52. The volume of the sound-absorbing cavity 52 and the cross-sectional area and length of the sound-absorbing shallow groove 54 are set so as to correspond to a predetermined noise frequency during traveling based on the Helmholtz resonance theory, thereby reducing noise at the frequency. Be able to.

  A 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. The corner 51 is formed with a second protrusion 58 that protrudes into the second circumferential groove 16. The corner 51 is an acute angle and is chamfered.

  As shown in FIGS. 8 and 9, the second protrusion 58 is inclined toward the groove bottom of the second circumferential groove 16 from an intermediate portion of the wall surface of the second land portion 50 on the second circumferential groove 16 side. An inclined surface 59 is provided. The second protrusion 58 extends in the same direction as the sound absorbing shallow groove 54 and is inclined with respect to the tire equatorial plane CL. As shown in FIG. 8, the second protrusion 58 has a triangular shape as viewed from the tire circumferential direction.

  It is preferable that the height H3 from the groove bottom on the wall surface side of the second land portion 50 of the second protrusion 58 is 30% to 70% of the groove depth H6 of the second circumferential groove 16. If the height H3 of the second protrusion 58 is less than 30% of the groove depth H6 of the second circumferential groove 16, the performance on snow cannot be effectively improved. Moreover, if it exceeds 70% of the groove depth H6 of the 2nd circumferential direction groove | channel 16, drainage performance and performance on snow cannot be made compatible efficiently. Therefore, the height H3 from the groove bottom on the wall surface side of the second land portion 50 of the second protrusion 58 is preferably 30% to 70% of the groove depth H6 of the second circumferential groove 16.

  The overhanging width W3 of the second protrusion 58 to the second circumferential groove 16 is preferably 10% to 50% of the groove width W6 of the second circumferential groove 16. If the overhang width W3 of the second protrusion 58 is less than 10% of the groove width W6 of the second circumferential groove 16, the performance on snow cannot be effectively improved. Further, if it exceeds 50% of the groove width W6 of the second circumferential groove 16, the drainage performance and the on-snow performance cannot be achieved efficiently. Therefore, the overhanging width W3 of the second protrusion 58 to the second circumferential groove 16 is preferably 10% to 50% of the groove width W6 of the second circumferential groove 16.

  An in-side shoulder land portion 60 is formed on the shoulder side of the third circumferential groove 18. A sipe 62 that is continuous in the tire circumferential direction is formed at the center in the tire width direction of the in-side shoulder land portion 60. A sipe 64 is formed between the sipe 62 and the third circumferential groove 18. The sipe 64 communicates with the sipe 62 and the third circumferential groove 18 and is disposed in a direction substantially parallel to the sipe 56 of the second land portion 50. Further, the sipe 64 is disposed at a position where the end portion on the third circumferential groove 18 side corresponds to the end portion of the sipe 56 on the third circumferential groove 18 side.

  A corner portion 61 is formed at a portion where the sipe 64 of the in-side shoulder land portion 60 and the third circumferential groove 18 intersect. The corner portion 61 is formed with a third protrusion 66 that protrudes into the third circumferential groove 18. The corner 61 is an acute angle and is chamfered. As shown in FIGS. 9 and 10, the third protrusion 66 is inclined from the middle portion of the wall surface on the third circumferential groove 18 side of the in-side shoulder land portion 60 toward the groove bottom of the third circumferential groove 18. An inclined surface 68 is provided. The third protrusion 66 extends in the same direction as the sipe 64 and is inclined with respect to the tire equatorial plane CL. As shown in FIG. 10, the third protrusion 66 has a triangular shape as viewed from the tire circumferential direction.

  An end shallow groove 63 is formed on the shoulder side of the sipe 62. The end shallow groove 63 is disposed so as to extend in the tire width direction. Two sipes 65 and 67 are formed between the adjacent end shallow grooves 63. The sipes 65 and 67 are connected by a sipe 69 disposed in the tire circumferential direction.

  The height H3 from the groove bottom on the wall surface side of the in-side shoulder land portion 60 of the third protrusion 66 is preferably 30% to 70% of the groove depth H7 of the third circumferential groove 18. If the height H4 of the third protrusion 66 is less than 30% of the groove depth H7 of the third circumferential groove 18, the performance on snow cannot be improved effectively. Moreover, if it exceeds 70% of the groove depth H7 of the 3rd circumferential groove | channel 18, drainage performance and snow performance cannot be made compatible efficiently. Therefore, the height H4 from the groove bottom on the wall surface side of the in-side shoulder land portion 60 of the third protrusion 66 is preferably 30% to 70% of the groove depth H7 of the third circumferential groove 18.

  The overhanging width W4 of the third protrusion 66 to the third circumferential groove 18 is preferably 10% to 50% of the groove width W7 of the third circumferential groove 18. If the overhang width W4 of the third protrusion 66 is less than 10% of the groove width W7 of the third circumferential groove 18, the performance on snow cannot be improved effectively. Moreover, if it exceeds 50% of the groove width W7 of the 3rd circumferential direction groove | channel 18, both drainage performance and on-snow performance cannot be achieved efficiently. Therefore, the overhanging width W4 of the third protrusion 66 to the third circumferential groove 18 is preferably 10% to 50% of the groove width W7 of the third circumferential groove 18.

  An out-side shoulder land portion 70 is formed on the shoulder side of the first circumferential groove 14. Sipes 72 and 74 that are continuous in the tire circumferential direction are separated from each other at the center in the tire width direction of the outer shoulder land portion 70.

  An end shallow groove 73 is formed slightly from the sipe 72 toward the shoulder side from the first circumferential groove 14 side. The end shallow groove 73 is disposed so as to extend in the tire width direction. A sipe 75 is formed between adjacent end shallow grooves 73.

  Sipes 76 and 77 are formed between the sipe 72 and the first circumferential groove 14. The sipe 76 is formed in the same direction as the end shallow groove 73 on the extension of the end shallow groove 73. One end of the sipe 77 communicates with the end of the sipe 75 and the sipe 72, the other end communicates with the first circumferential groove 14, and is disposed in a direction substantially parallel to the lug groove 30.

  A cutout 79 is formed at a position corresponding to the lug groove 30 on the outboard shoulder land portion 70 on the first circumferential groove 14 side.

(Function)
Next, the effect | action of the pneumatic tire 10 of this embodiment is demonstrated.
In the pneumatic tire 10 of the present embodiment, the tread 12 is provided with three circumferential grooves including a first circumferential groove 14, a second circumferential groove 16, and a third circumferential groove 18 extending along the tire circumferential direction. As a result of the arrangement, basic drainage performance, straight running stability during dry and wet running are ensured.

  And since the lug groove 30 which inclines at 25-65 degree | times with respect to the tire circumferential direction is arrange | positioned at the tread 12, the drainage performance higher than the conventional all-season tire can be exhibited. Furthermore, noise can be suppressed.

  Moreover, since the lug groove 30 is comprised so that a groove width may become wide toward the 1st circumferential direction groove | channel 14, the drainage property toward the 1st circumferential direction groove | channel 14 can be improved.

  Further, since the lug groove 30 is curved in a direction in which the angle of the corner portion 24 increases, the lug groove 30 is directed from the lug groove 30 toward the first circumferential groove 14 as compared with a case where the lug groove is linear. Distance can be shortened and drainage can be improved.

  Moreover, since the level difference part 40 is formed in the division land part 22 facing the lug groove 30 on the corner part 24 side, the rigidity of the division land part 22 is ensured while ensuring drainage performance in the lug groove 30. It is possible to improve and suppress collapse.

  In the present embodiment, the stepped portion 40 is formed only on the corner portion 24 side, but a stepped portion having the same configuration as the stepped portion 40 may be formed on the stepped side end of the land section 22. .

  In addition, by making the second circumferential groove 16 side of the lug groove 30 a shallow groove 30A having a shallower groove bottom than the first circumferential groove 14 side, a portion close to the tire equatorial plane CL of the tread 12 (the contact pressure) By increasing the strength of the high portion), the strength of the land section 22 can be effectively increased.

  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. Since the third protrusion 66 is provided, the traction performance and the braking performance on snow can be improved as compared with the case without these protrusions. At the same time, the groove volume of the first circumferential groove 14, the second circumferential groove 16, and the third circumferential groove 18 can be secured, and the drainage can be secured.

  In the present embodiment, the first protrusion 46, the second protrusion 58, and the third protrusion 66 are provided in each of the first circumferential groove 14, the second circumferential groove 16, and the third circumferential groove 18. However, any one or two of the grooves may be provided with protrusions.

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

  Note that, instead of the sound absorption cavity 52 of the present embodiment, the sound absorption cavity 80 shown in FIG. And you may comprise the groove | channel 82 extended in the kick-out direction from the intermediate part of the sound absorption cavity part 80, and connected with the 2nd circumferential groove | channel 16.

Regarding the pneumatic tire according to the above-described embodiment (Example) and the pneumatic tire having a tread disclosed in Japanese Patent No. 3229295 (Comparative Example), the performance on snow and steering stability performance were evaluated. The performance on snow was measured by measuring on-snow acceleration and braking distance on a flat straight road test course. Steering performance was evaluated by feeling evaluation by a test driver in a undulating circumferential circuit (dry). In each evaluation, the comparative example was set to 100, and the evaluation was based on an index. The higher the value, the better the performance.
The tire size was 225 / 45R17 in all cases.

  From Table 1, it is clear that the pneumatic tires of the examples have high performance in terms of performance on snow and steering stability.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 1st circumferential groove 16 2nd circumferential groove 18 3rd circumferential groove 20 Land part 22 Compartment land part 30 Lug groove 30A Shallow groove 40 Step part 46 First protrusion 48 Inclined surface 50 First 2 land portion 52 sound absorption cavity portion 58 second protrusion 66 third protrusion

Claims (10)

A plurality of circumferential grooves provided on the tread and extending along the tire circumferential direction;
An outermost circumferential groove disposed on one outermost side in the tire width direction, and a land portion configured between the outermost circumferential groove and a second circumferential groove adjacent to the outermost circumferential groove;
A plurality of lug grooves extending from the outermost circumferential groove toward the tire equatorial plane and inclined with respect to the tire equatorial plane and arranged at intervals in the tire circumferential direction,
On the side where the corner on the outermost circumferential groove side of the partition land part where the land part is partitioned in the tire circumferential direction by the lug groove is an acute angle, the groove of the lug groove faces the lug groove. A pneumatic tire characterized in that a stepped portion that rises from the bottom and has a stepped surface lower than the tread of the division land portion is formed from the outermost circumferential groove toward the tire equatorial plane.   2. The pneumatic tire according to claim 1, wherein the lug groove is inclined at an angle of 20 ° to 60 ° with respect to a tire equatorial plane.   The pneumatic tire according to claim 1 or 2, wherein a protruding width of the stepped portion to the lug groove is 10% to 50% of an average groove width of the lug groove.   The height from the groove bottom of the said lug groove of the said level | step-difference part is 30%-70% of the depth of the outermost circumferential groove side of the said lug groove, The any one of Claims 1-3 characterized by the above-mentioned. The pneumatic tire according to claim 1.   The lug groove is configured to communicate with the second circumferential groove, and the second circumferential groove side is a shallow groove shallower than the outermost circumferential groove side. The pneumatic tire according to any one of 1 to 4.   Three of the circumferential grooves are formed in the tread, one of the circumferential grooves is disposed on one side with respect to the tire equatorial plane to be the outermost circumferential groove, and the other two are The pneumatic tire according to claim 1, wherein the pneumatic tire is disposed on the other side with respect to the tire equator plane.   The pneumatic tire according to any one of claims 1 to 6, wherein the lug groove is configured so that a groove width becomes wider toward the outermost circumferential groove.   The pneumatic according to any one of claims 1 to 7, wherein the lug groove is curved in a direction in which an inclination angle with respect to a tire equatorial plane gradually increases toward the outermost circumferential groove. tire.   9. The shallow land groove shallower than the outermost circumferential groove side is formed in the partition land portion so as to communicate between the lug grooves adjacent to each other in the tire circumferential direction. A pneumatic tire given in any 1 paragraph. A second land portion configured between the second circumferential groove and the circumferential groove on the opposite side to the outermost circumferential groove;
A plurality of sound absorbing parts having a resonance cavity part and a communication groove communicated with the resonance cavity part and the second circumferential groove in the second land part are configured along the tire circumferential direction, The pneumatic tire according to claim 1.

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