JP5923125B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that achieves both wet performance and steering stability.

  Patent Literature 1 below proposes a pneumatic tire in which a tread portion is provided with a lug groove having one end communicating with the main groove and the other end terminating in the land portion. Such a lug groove maintains the rigidity of a land part high compared with the horizontal groove which communicates between the main grooves adjacent in a tire axial direction, and improves steering stability.

  However, such lug grooves may reduce wet performance. For this reason, even if it was the pneumatic tire of patent document 1, there was room for the further improvement about coexistence with wet performance and steering stability.

JP 2012-188080 A

  The present invention has been devised in view of the above situation, and provides a pneumatic tire that achieves both wet performance and steering stability by improving a lug groove provided in a middle land portion. This is the main purpose.

According to the present invention, a pair of shoulder main grooves extending continuously in the tire circumferential direction on the tread ground end side most at the tread portion, and at least one extending continuously in the tire circumferential direction on the inner side in the tire axial direction than the shoulder main grooves A pneumatic tire in which a pair of middle land portions between the shoulder main groove and the center main groove is divided by providing a center main groove, and one end of the middle land portion has one end. An inner middle lug groove that communicates with the center main groove and has an outer end that terminates in the middle land portion; an inner end that communicates with the shoulder main groove and an inner end that terminates within the middle land portion; and the inner middle lug groove, Outer middle lug grooves that are inclined in the same direction are alternately provided in the tire circumferential direction, and each inner middle lug groove has an angle θ1 of 20 to 45 ° with respect to the tire circumferential direction. Communicating with the terpolymer main groove, wherein each outer middle lug groove, and communicates with the shoulder main grooves at an angle θ2 of 60-80 ° with respect to the tire circumferential direction, the inner middle lug groove is communicated with the center main groove and A bent groove including a first portion extending at the angle θ1 and a second portion provided on the outer side in the tire axial direction of the first portion and extending at an angle θ3 larger than the angle θ1 with respect to the tire circumferential direction. It is characterized in that.

The middle land portion of the pneumatic tire of the present invention is provided with a middle lag sipe whose outer end in the tire axial direction communicates with the shoulder main groove and whose inner end in the tire axial direction terminates in the middle land portion. Preferably, the middle lag sipe is provided between the outer middle lag groove and the inner middle lag groove adjacent in the tire circumferential direction, and is inclined in the same direction as the outer middle lag groove.

  In the pneumatic tire of the present invention, it is preferable that the second portion extends substantially parallel to the outer middle lug groove.

  In the pneumatic tire of the present invention, it is desirable that the length of the first portion in the tire axial direction is 0.25 to 0.50 times the width of the middle land portion in the tire axial direction.

  In the pneumatic tire of the present invention, it is preferable that the inner end of the outer middle lug groove is located on the inner side in the tire axial direction with respect to the outer end of the inner middle lug groove.

  In the pneumatic tire according to the present invention, the middle land portion is provided with a middle concave portion in which an edge on the center main groove side is recessed between the inner middle lug grooves, and the inner end of the outer middle lug groove and It is desirable that a sipe connecting the middle recess is provided.

  The pneumatic tire of the present invention has a pair of shoulder main grooves extending continuously in the tire circumferential direction at the tread ground end side most continuously on the tread portion, and continuously in the tire circumferential direction on the inner side in the tire axial direction than the shoulder main grooves. By providing at least one center main groove that extends, a pair of middle land portions between the shoulder main groove and the center main groove are separated. The middle land portion has an inner middle lug groove with one end communicating with the center main groove and an outer end terminating in the middle land portion, one end communicating with the shoulder main groove and the inner end terminating in the middle land portion, and Outer middle lug grooves inclined in the same direction as the inner middle lug grooves are alternately provided in the tire circumferential direction. Such an inner middle lug groove and an outer middle lug groove improve the wet performance while maintaining the rigidity of the middle land portion.

  Each inner middle lug groove communicates with the center main groove at an angle θ1 of 20 to 45 ° with respect to the tire circumferential direction. Such an inner middle lug groove discharges water in the center main groove to the outer side in the tire axial direction during wet running, thereby improving wet performance.

  Each outer middle lug groove communicates with the shoulder main groove at an angle θ2 of 60 to 80 ° with respect to the tire circumferential direction. Such an outer middle lug groove maintains rigidity on the outer side in the tire axial direction of the middle land portion, and improves steering stability.

  Therefore, the pneumatic tire of the present invention achieves both wet performance and steering stability.

It is an expanded view of the tread part of the pneumatic tire of this embodiment. It is AA sectional drawing of FIG. It is an enlarged view of the middle land part of FIG. It is an expansion perspective view of the middle recessed part of FIG. It is an enlarged view of the center land part of FIG. It is an expansion perspective view of the center recessed part of FIG. It is an enlarged view of the shoulder land part of FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a tread portion 2 of a pneumatic tire (hereinafter sometimes simply referred to as “tire”) 1 of the present embodiment. The pneumatic tire 1 of this embodiment is suitably used as a pneumatic tire for passenger cars, for example.

  As shown in FIG. 1, the tread portion 2 is provided with a pair of shoulder main grooves 3 and 3 and a pair of center main grooves 4 and 4.

  The shoulder main grooves 3 and 3 continuously extend in the tire circumferential direction on both sides of the tire equator C and on the most tread ground contact end Te side. The shoulder main groove 3 of the present embodiment has a substantially constant groove width W1 and extends linearly.

  The “tread grounding end Te” is assembled with a normal rim (not shown) and filled with a normal internal pressure, and a normal load is applied to the normal tire 1 in an unloaded state so that the camber angle is 0 °. This is the ground contact position on the outermost side in the tire axial direction when grounding on the plane.

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

  The “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum value described in “AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO.

  The “regular load” is a load determined by each standard for each tire in the standard system including the standard on which the tire is based. “JATMA” indicates “maximum load capacity”, and TRA indicates “TIRE LOAD”. The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “LOAD CAPACITY” in the case of ETRTO.

  The center main groove 4 extends continuously in the tire circumferential direction on the inner side in the tire axial direction than the shoulder main groove 3. A pair of center main grooves 4 of the present embodiment are provided on both sides of the tire equator C. For example, only one center main groove 4 may be provided on the tire equator C. The center main groove 4 has, for example, a substantially constant groove width W2 and extends linearly.

  The groove width W1 of the shoulder main groove 3 and the groove width W2 of the center main groove 4 are, for example, 2.5 to 7.5% of the tread ground contact width TW. Such shoulder main groove 3 and center main groove 4 effectively drain the water film between the road surface and the tread portion 2 during wet running, and improve the wet performance. The tread contact width TW is a distance in the tire axial direction between the tread contact ends Te and Te of the tire 1 in a normal state.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the groove depths d <b> 1 and d <b> 2 of the shoulder main groove 3 and the center main groove 4 are preferably about 5 to 10 mm, for example, in the case of the passenger car tire of this embodiment.

  As shown in FIG. 1, the tread portion 2 is provided with a shoulder main groove 3 and a center main groove 4, thereby dividing the middle land portion 10, the center land portion 20, and the shoulder land portion 30.

  FIG. 3 shows an enlarged view of the middle land portion 10. As shown in FIG. 3, each middle land portion 10 is provided between the shoulder main groove 3 and the center main groove 4. Each middle land portion 10 is provided with inner middle lug grooves 11 and outer middle lug grooves 12 alternately in the tire circumferential direction.

  The inner middle lug groove 11 is inclined with respect to the tire circumferential direction. The inner middle lug groove 11 has an inner end 11 a in the tire axial direction communicating with the center main groove 4, and an outer end 11 o in the tire axial direction terminates in the middle land portion 10.

  The outer middle lug groove 12 is inclined in the same direction as the inner middle lug groove 11. The outer middle lug groove 12 has an outer end 12 a in the tire axial direction communicating with the shoulder main groove 3, and an inner end 12 i in the tire axial direction ends in the middle land portion 10.

  Such an inner middle lug groove 11 and an outer middle lug groove 12 improve wet performance while preventing a decrease in rigidity of the middle land portion 10.

  Each inner middle lug groove 11 communicates with the center main groove 4 at an angle θ1 of 20 to 45 ° with respect to the tire circumferential direction. Such an inner middle lug groove 11 efficiently drains the water in the center main groove 4 to the outer side in the tire axial direction during wet running, thereby improving wet performance.

  In order to improve the wet performance while maintaining the rigidity of the middle land portion 10, the angle θ1 is preferably 25 ° or more, more preferably 30 ° or more, preferably 40 ° or less, more preferably 35 ° or less. is there.

  Each outer middle lug groove 12 communicates with the shoulder main groove 3 at an angle θ2 of 60 to 80 ° with respect to the tire circumferential direction. Such an outer middle lug groove 12 maintains the rigidity of the middle land portion 10 on the outer side in the tire axial direction, and improves steering stability.

  In order to achieve a better balance between wet performance and steering stability, the angle θ2 is preferably 65 ° or more, more preferably 68 ° or more, preferably 75 ° or less, more preferably 72 ° or less. .

  The inner middle lug groove 11 of the present embodiment is a bent groove including a first portion 13 and a second portion 14, for example.

  The first portion 13 communicates with the center main groove 4 and extends linearly at the angle θ1. The length L1 of the first portion 13 in the tire axial direction is preferably not less than 0.25 times, more preferably not less than 0.35 times, preferably not less than 0.35 times the width W3 of the middle land portion 10 in the tire axial direction. 50 times or less, more preferably 0.45 times or less. Such first portion 13 improves wet performance and steering stability in a well-balanced manner.

  The second portion 14 extends at an angle θ3 larger than the angle θ1 with respect to the tire circumferential direction. Thereby, during wet running, the water in the center main groove 4 is effectively guided outward in the tire axial direction, and wet performance is improved.

  The angle θ3 of the second portion 14 is preferably 60 ° or more, more preferably 65 ° or more, preferably 80 ° or less, more preferably 75 ° or less. Such a second portion 14 improves the wet performance while maintaining the rigidity of the middle land portion 10.

  The second portion 14 preferably extends substantially parallel to the outer middle lug groove 12. Such a second portion 14 makes the rigidity distribution of the middle land portion 10 uniform, and suppresses uneven wear of the middle land portion 10.

  It is desirable that the groove width W5 of the inner middle lug groove 11 gradually decreases toward the outer side in the tire axial direction. The edge of the outer end 11o of the inner middle lug groove 11 of the present embodiment is formed in an arc shape, for example. Such an inner middle lug groove 11 maintains the rigidity of the middle land portion 10 and improves steering stability. The groove width W5 of the inner middle lug groove 11 of the present embodiment is, for example, 3.0 to 6.0 mm.

  For example, the outer middle lug groove 12 desirably extends substantially linearly at the angle θ2. Such an outer middle lug groove 12 exhibits excellent wet performance.

  The outer middle lug groove 12 is preferably curved and terminated at the inner end 12t in the tire axial direction, for example. Such an outer middle lug groove 12 effectively suppresses cracks in the middle land portion 10 starting from the inner end 12i.

  The inner end 12 i of the outer middle lug groove 12 is preferably located on the inner side in the tire axial direction from the outer end 11 o of the inner middle lug groove 11. Such an outer middle lug groove 12 further improves wet performance.

  It is desirable that the groove width W6 of the outer middle lug groove 12 is gradually reduced toward the inner side in the tire axial direction. Such an outer middle lug groove 12 maintains the rigidity of the middle land portion 10 and improves steering stability. The groove width W6 of the outer middle lug groove 12 of the present embodiment is, for example, 3.0 to 6.0 mm.

  The middle land portion 10 of the present embodiment is further provided with a middle concave portion 15.

  The middle recess 15 is provided between the inner middle lug grooves 11 and 11 adjacent to each other in the tire circumferential direction. The middle concave portion 15 is formed by denting the edge 10 e of the middle land portion 10 on the center main groove 4 side.

  FIG. 4 shows an enlarged perspective view of the middle recess 15. As shown in FIG. 4, the middle concave portion 15 is formed by denting the middle land portion 10 in a substantially tetrahedral space composed of four triangular surfaces. The middle recess 15 includes a recess bottom surface 18 and a recess side wall surface 19.

  For example, it is desirable that the recess bottom surface 18 is smoothly connected to the tread surface 10 s of the middle land portion 10. The recess bottom surface 18 of the present embodiment is inclined with respect to the tread surface 10s, and the depth of the middle recess 15 is gradually increased to one side or the other side in the tire circumferential direction.

  The recess side wall surface 19 continues to the recess bottom surface 18 substantially perpendicularly. The recess side wall surface 19 extends along the tire radial direction. The concave side wall surface 19 is, for example, a flat surface or a curved surface that is gently curved.

  The middle concave portion 15 including the concave bottom surface 18 and the concave side wall surface 19 supplements the drainage performance of the adjacent main groove and further improves the wet performance.

  As shown in FIG. 3, a connection sipe 16 is further provided in the middle land portion of the present embodiment. For example, the connection sipe 16 extends linearly. The connection sipe 16 connects, for example, the inner end 12 i of the outer middle lug groove 12 and the middle recess 15. Such a connection sipe 16 guides the water in the middle concave portion 15 to the outside in the tire axial direction during wet traveling, thereby improving the wet performance. In this specification, the “sipe” is a cut having a width of about 1 mm or less, which is substantially free of width, and is distinguished from a draining groove.

  A middle lag sipe 17 is further provided in the middle land portion 10 of the present embodiment. The middle lag sipe 17 has an outer end 17 a in the tire axial direction communicating with the shoulder main groove 3, and an inner end 17 i in the tire axial direction terminates in the middle land portion 10. The middle lag sipe 17 is preferably inclined in the same direction as the outer middle lag groove 12, for example. The middle lag sipe 17 of this embodiment extends substantially parallel to the main part of the outer middle lag groove 12. Such a middle lag sipe 17 improves the wet performance while maintaining the rigidity of the middle land portion 10 and improving the steering stability.

  The middle lug sipe 17 is preferably provided between the outer middle lug groove 12 and the inner middle lug groove 11 which are adjacent in the tire circumferential direction. Such a middle lag sipe 17 makes the rigidity distribution of the middle land portion 10 uniform, and suppresses uneven wear of the middle land portion 10.

  FIG. 5 shows an enlarged view of the center land portion 20. The center land portion 20 is divided between the pair of center main grooves 4 and 4. The center land portion 20 is, for example, a rib continuous in the tire circumferential direction. Such a center land portion 20 exhibits excellent steering stability.

  For example, a center sub-groove 21 is provided in the center land portion 20 of the present embodiment.

  For example, the center sub-groove 21 extends linearly continuously in the tire circumferential direction. The center sub-groove 21 is desirably provided on the tire equator C, for example. The groove width W9 of the center sub-groove 21 is 6 to 12% of the width W8 of the center land portion 20, for example. The groove depth d3 (shown in FIG. 2) of the center sub-groove 21 is, for example, 4 to 6 mm. Such a center sub-groove 21 exhibits excellent wet performance while maintaining the rigidity of the center land portion 20.

  In the center land portion 20 of the present embodiment, center recesses 22 are spaced apart in the tire circumferential direction. FIG. 6 shows an enlarged perspective view of the center recess 22. As shown in FIG. 6, the center recess 22 is formed by recessing the edges 20 e and 20 e on both sides of the center land portion 20. The center recessed part 22 is recessed in the space of the substantially tetrahedron which consists of the center land part 20 from four triangular surfaces. The center recess 22 has substantially the same shape as the middle recess 15 (shown in FIG. 4).

  FIG. 7 shows an enlarged view of the shoulder land portion 30. As shown in FIG. 7, the shoulder land portion 30 is provided outside the shoulder main groove 3 in the tire axial direction.

  The shoulder land portion 30 includes a rib region 31 and a block region 32. The rib region 31 has a rib shape extending continuously in the tire circumferential direction. In the block region 32, blocks divided by lateral grooves and sipes are spaced apart in the tire circumferential direction. The block area 32 is provided outside the rib area 31 in the tire axial direction.

  The ratio W10 / W11 between the width W10 of the rib region 31 in the tire axial direction and the width W11 of the block region 32 in the tire axial direction is preferably 0.2 or more, more preferably 0.23 or more, and preferably 0.0. 3 or less, more preferably 0.27 or less. Such rib region 31 and block region 32 improve wandering performance while maintaining steering stability performance.

  The shoulder land portion 30 is provided with a shoulder lateral groove 33, a shoulder longitudinal sipe 34, and a shoulder lateral sipe 35.

  The shoulder lateral groove 33 extends, for example, at least from the tread ground contact end Te inward in the tire axial direction. For example, the shoulder lateral groove 33 preferably terminates in the shoulder land portion 30. For example, the shoulder lateral groove 33 of the present embodiment is gently curved. Such a shoulder lateral groove 33 achieves both steering stability performance and wandering performance.

  For example, the shoulder vertical sipe 34 communicates between the shoulder lateral grooves 33 and 33. The shoulder vertical sipe 34 of the present embodiment communicates with the inner end 33 i of the shoulder lateral groove 33 in the tire axial direction. Such a shoulder vertical sipe 34 exhibits excellent wet performance.

  The shoulder lateral sipe 35 is provided between, for example, shoulder lateral grooves 33, 33 adjacent to each other in the tire circumferential direction, and extends along the shoulder lateral groove 33. The shoulder lateral sipe 35 extends, for example, at least from the tread contact end Te inward in the tire axial direction, and terminates in the shoulder land portion 30. Such a shoulder lateral sipe 35 improves wandering performance.

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to said specific embodiment, It changes and implements to various aspects.

A pneumatic tire for passenger cars of size 225 / 65R17 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1. As Comparative Example 1, a tire in which each lug groove was provided at an angle of 90 ° with respect to the tire circumferential direction was manufactured. These tires were mounted on the following test vehicles and tested for wet performance and handling stability. The common specifications and test methods for each tire are as follows.
Wearing rim: 17 × 6.5J
Tire internal pressure: 220kPa
Test vehicle: 4-wheel drive vehicle, displacement 2400cc
Tire mounting position: all wheels

<Wet performance>
The lateral G of the front wheel was measured when the test vehicle was entered on a test course on an asphalt road surface with a radius of 100 m provided with a puddle having a depth of 5 mm and a length of 20 m. Moreover, the average lateral G of the front wheels when the traveling speed of the test vehicle is 50 to 80 km / h was calculated. A result is an index | exponent which makes the said average horizontal G of the comparative example 1 100, and shows that wet performance is excellent, so that a numerical value is large.

<Steering stability>
Steering stability when driving on a dry asphalt road surface with the test vehicle was evaluated by the driver's sensuality. A result is a score which sets the comparative example 1 to 100, and shows that steering stability is excellent, so that a numerical value is large.

  As a result of the test, it was confirmed that the pneumatic tires of the examples achieved a good balance between wet performance and steering stability.

2 Tread part 3 Shoulder main groove 4 Center main groove 10 Middle land part 11 Inner middle lug groove 12 Outer middle lug groove

Claims (6)

A pair of shoulder main grooves extending continuously in the tire circumferential direction on the tread ground end side most at the tread portion, and at least one center main extending continuously in the tire circumferential direction on the inner side in the tire axial direction than the shoulder main grooves A pneumatic tire in which a pair of middle land portions between the shoulder main groove and the center main groove are divided by providing a groove,
The middle land portion has an inner middle lug groove whose one end communicates with the center main groove and whose outer end terminates in the middle land portion,
One end communicates with the shoulder main groove and the inner end terminates in the middle land portion, and outer middle lug grooves inclined in the same direction as the inner middle lug groove are alternately provided in the tire circumferential direction,
Each of the inner middle lug grooves communicates with the center main groove at an angle θ1 of 20 to 45 ° with respect to the tire circumferential direction.
Each outer middle lug groove, and communicates with the shoulder main grooves at an angle θ2 of 60-80 ° with respect to the tire circumferential direction,
The inner middle lug groove is provided on the outer side in the tire axial direction of the first portion, communicating with the center main groove and extending at the angle θ1, and more than the angle θ1 with respect to the tire circumferential direction. A pneumatic tire comprising a bent groove including a second portion extending at a large angle θ3 . The middle land portion is provided with a middle lag sipe whose outer end in the tire axial direction communicates with the shoulder main groove, and whose inner end in the tire axial direction terminates in the middle land portion,
The pneumatic tire according to claim 1, wherein the middle lug sipe is provided between the outer middle lug groove and the inner middle lug groove that are adjacent to each other in the tire circumferential direction, and is inclined in the same direction as the outer middle lug groove. .   The pneumatic tire according to claim 2, wherein the second portion extends substantially parallel to the outer middle lug groove.   The pneumatic tire according to claim 2 or 3, wherein a length of the first portion in the tire axial direction is 0.25 to 0.50 times a width of the middle land portion in the tire axial direction.   The pneumatic tire according to any one of claims 1 to 4, wherein the inner end of the outer middle lug groove is positioned on the inner side in the tire axial direction than the outer end of the inner middle lug groove. The middle land portion is provided with a middle concave portion in which an edge on the side of the center main groove is recessed between the inner middle lug grooves,
The pneumatic tire according to any one of claims 1 to 5, further comprising a sipe that connects the inner end of the outer middle lug groove and the middle recess.

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