JP2010184570A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a wet hydroplaning performance, a land part rigidity and an on-ice performance of a pneumatic tire. <P>SOLUTION: A steep slanted lug sipe 18 having a certain orientation is formed on a land part 16 between a pair of peripheral major sipes 14, and tapered segments 22, 24 slanted toward the sipes and having their widths narrowed from a treading side to a kicking side are formed on end edges of the steep slanted lug sipe 18 and the peripheral major sipes 14. Water on the treading surface flows smoothly from the treading side toward the licking side into the sipes through these tapered segments to improve a wet hydro planing performance. Since a sipe wall strength is assured by the tapered segments 22 while keeping a large area of the steep slanted lug sipes 18, it is possible to keep a water draining characteristic without arranging any peripheral major sipes on a tire equatorial plane and at the same time to assure a braking characteristic and an operating stability through improvement of a land part rigidity. In addition, it is possible to improve an on-snow running performance since some snow columns with a certain strength can be formed at the tapered segments 22, 24 at the time of on-snow running operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved wet hydroplaning performance, land rigidity, and snow performance.

  As a conventional pneumatic tire, a method of forming a groove inclined with respect to the circumferential direction is known in order to aim at effective drainage with respect to a tire whose rotation direction is specified (see, for example, Patent Document 1). ).

In order to ensure braking and steering stability, it is preferable that the tire equatorial plane is a land portion.

JP-A-8-104110

  In the case of a tire whose rotation direction is specified, when it is intended to improve braking and steering stability, a groove inclined to the circumferential direction is formed and the land portion is connected to the land portion near the tire equator plane. Although rigidity can be ensured, if further drainage is to be ensured, the groove area near the equator of the tire must be increased, but at the same time, the rigidity of the land portion will be reduced, making it impossible to ensure braking and steering stability. .

  The present invention has been made to solve the above problems, and an object thereof is to provide a pneumatic tire with improved wet hydroplaning performance, land rigidity, and on-snow performance.

  The present invention has been made in view of the above-described facts, and the pneumatic tire according to claim 1 is disposed on both sides of a tread that contacts a road surface and a tire equatorial plane of the tread, and extends along a tire circumferential direction. A plurality of circumferential main grooves extending in the tread, extending from the circumferential main groove closest to the tire equatorial plane toward the tire equatorial plane and terminating in the land, and an end on the tire equatorial plane side A plurality of inclined lug grooves that incline with respect to the tire axial direction so as to come into contact with the tire axially outer end, an edge on the inclined lug groove side of the land portion of the tread, and a circumferential main groove side The taper portion is formed on the edge of the tire and is inclined toward the groove side and narrowed from the stepping side toward the kicking-out side, and is provided on the tire equatorial surface of the tread, in the tire circumferential direction. With a continuous land part, That.

Next, the operation of the pneumatic tire according to claim 1 will be described.
The tread of the pneumatic tire according to claim 1 includes a plurality of circumferential main grooves disposed on both sides of the tire equatorial plane and extending along the tire circumferential direction, and a circumferential main groove closest to the tire equatorial plane. A plurality of inclined lug grooves that extend toward the equator plane and terminate in the land portion, and are inclined with respect to the tire axial direction so that the end portion on the tire equator plane side comes in contact with the end portion on the outer side in the tire axial direction; Since the directional pattern is formed on the wet road surface, the water in the ground contact surface is efficiently discharged through the circumferential main groove and the inclined lug groove when the wet road surface is traveled, and the wet hydroplaning performance is ensured.

  Moreover, since the taper part inclined toward the groove side is formed in the edge part on the inclined lug groove side and the end edge on the circumferential main groove side in the land part, the part in which the taper part is formed In this case, the groove width is substantially enlarged, and the tapered portion is formed to have a narrow width from the stepping side to the kicking side, so that the tread surface from the stepping side to the kicking side is formed. The water on the side flows smoothly into the groove through the tapered portion, and the wet hydroplaning performance is improved.

In addition, an inclined lug groove is formed in the land portion between the circumferential main grooves, but the inclined lug groove does not cross the land portion and is continuous in the circumferential direction on the tire equatorial plane. There is a land part. And the land portion between the circumferential main grooves can secure the groove wall strength by the tapered portion while taking a large area of the inclined lug groove, and ensuring drainage without providing the circumferential main groove on the tire equatorial plane. At the same time, braking performance and steering stability can be ensured by improving the rigidity of the land near the tire equator plane.
Furthermore, when driving on snow, snow enters the circumferential main grooves and slant lug grooves in the ground contact surface, and a strong snow column can be formed at the tapered part, so that the land part is caught by the snow column and the performance on the snow is improved. Improvements can be made.

  Thereby, wet hydroplaning performance, block rigidity, and performance on snow can be improved.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, when the tapered portion is viewed in a cross section along the groove width direction, a contour portion of the tapered portion has a recessed central portion.

Next, the operation of the pneumatic tire according to claim 2 will be described.
By denting the central part of the taper part, an effective edge effect can be obtained during running on snow, and at the same time, a strong snow column can be formed in the groove, and the running performance on snow can be improved. .

  As described above, according to the pneumatic tire of the present invention, there is an excellent effect that wet hydroplaning performance, land portion rigidity, and performance on snow can be improved.

It is a top view of the tread of the pneumatic tire concerning one embodiment of the present invention. (A) is the sectional view on the AA line of FIG. 1, (B) is the sectional view on the BB line of FIG. It is a top view of the tread of the pneumatic tire concerning a conventional example. 5 is a plan view of a tread of a pneumatic tire according to Comparative Example 1. FIG. 5 is a plan view of a tread of a pneumatic tire according to Comparative Example 2. FIG.

Hereinafter, a pneumatic tire 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, circumferential main grooves 14 extending along the tire circumferential direction are disposed on both sides of the tire equatorial plane CL in the tread 12 of the pneumatic tire 10 of the present embodiment. Reference numeral 12E denotes a ground end of the tread 12. In the present embodiment, two circumferential main grooves 14 are formed, but in some cases, four or more may be formed.

In the land portion 16 between the pair of circumferential main grooves 14, steeply inclined lug grooves 18 extending from the circumferential main grooves 14 toward the tire equatorial plane CL are inclined with respect to the tire axial direction. It is formed on both sides of the tire equatorial plane CL at intervals in the direction.
These steeply inclined lug grooves 18 end at one end on the tire equatorial plane CL side in the land 16 near the tire equatorial plane CL, and the other end is connected to the circumferential main groove 14. The steeply inclined lug groove 18 is inclined in a direction in which the end portion on the tire equatorial plane CL side contacts the ground before the end portion on the circumferential main groove 14 side when the tire rotates.

The steeply inclined lug groove 18 on one side and the steeply inclined lug groove 18 on the other side of the tire equatorial plane CL are arranged with a phase difference in the circumferential direction, and the land portion 16 has a central portion in the tire axial direction. It is continuous without being divided in the tire circumferential direction.
Further, in the land portion 16 between the pair of circumferential main grooves 14, a first gently inclined lag groove 20 having a smaller angle with respect to the tire axial direction than the steeply inclined lug groove 18 is provided in the tire circumferential direction. Are formed on both sides of the tire equatorial plane CL with a gap therebetween. In the present embodiment, there are a first gently inclined lug groove 20 whose end is connected to the circumferential main groove 14 and a first gently inclined lug groove 20 that intersects the circumferential main groove 14. Note that the tire equatorial plane CL side of the first gently inclined lug groove 20 terminates in the vicinity of the tire equatorial plane CL.

Further, the land portion 16 between the pair of circumferential main grooves 14 has a groove on an end edge on the steeply inclined lug groove 18 side (outer side in the tire axial direction when viewed from the groove center line of the steeply inclined lug groove 18). A first taper portion 22 is formed which is inclined toward the side and whose width (W shown in FIG. 2) is narrowed from the step-in side toward the kick-out side, and the end on the circumferential main groove 14 side is formed. A second taper portion 24 that is inclined toward the groove side and whose width (W shown in FIG. 2) is narrowed from the stepping side to the kicking side is formed at the edge.
The first tapered portion 22 of the present embodiment is formed from the end portion of the steeply inclined lug groove 18 on the tire equatorial plane side toward the kicking side, and extends to the middle portion in the longitudinal direction of the steeply inclined lug groove 18. It extends. Further, the second tapered portion 24 of the present embodiment is formed from the end of the steeply inclined lug groove 18 on the circumferential main groove side toward the kicking side.

As shown in the cross-sectional view of FIG. 2A, the outer surface in the tire radial direction of the first tapered portion 22 of the present embodiment has a shape in which the central portion is recessed when viewed in a cross section along the groove width direction. Specifically, it is formed in a substantially arc shape having a center of curvature outside the tire. Further, as shown in the cross-sectional view of FIG. 2B, the outer surface in the tire radial direction of the second tapered portion 24 of the present embodiment is also a cross section along the groove width direction, like the first tapered portion 22. , The center portion has a concave shape, more specifically, a substantially arc shape having a center of curvature on the outer side of the tire. In the present embodiment, the first taper portion 22 and the second taper portion 24 have a shape in which the central portion is recessed, but the height may be gradually reduced toward the groove, as seen in a cross section. Sometimes it may be linear.
In the land portion 16 between the pair of circumferential main grooves 14, a sipe 26 parallel to the first gently inclined lug groove 20 is formed between the first gently inclined lug grooves 20. .

As shown in FIG. 1, in the land portion 28 on the outer side in the tire axial direction of the circumferential main groove 14, a second gently inclined lug groove 30 and a third gently inclined lug groove 32 that are inclined with respect to the tire axial direction. Are alternately formed in the tire circumferential direction, and sipes 34, 36 substantially parallel to these lug grooves are formed between the second gently inclined lug grooves 30 and the third gently inclined lug grooves 32. ing.
Note that, similarly to the steeply inclined lug groove 18, the second gently inclined lug groove 30 and the third gently inclined lug groove 32 are inclined so that the end portion on the tire equatorial plane side comes into contact with the ground first.
The land portion 16 has a land portion that is continuous in the tire circumferential direction on the tire equatorial plane CL.

(Function)
In the pneumatic tire 10 of the present embodiment, the circumferential main groove 14 disposed on both sides of the tire equatorial plane CL extends toward the circumferential main groove 14 from the tire equatorial plane CL side and is on the tire equatorial plane side. A plurality of steeply inclined lug grooves 18, a first slowly inclined lug groove 20, and a second gently inclined lug that are inclined with respect to the tire axial direction so that the end portion of the tire is grounded before the end portion outside the tire axial direction Since the directional pattern is formed by the groove 30 and the third gently sloping lug groove 32, the water in the ground contact surface is efficiently discharged through these grooves when running on the wet road surface, and the wet hydroplaning performance. Is secured.

The land portion 16 between the pair of circumferential main grooves 14 includes a steeply inclined lug groove 18 on an outer edge in the tire axial direction and an end edge on the inner side in the tire axial direction of the circumferential main groove 14 on the groove side. Since the taper portion 22 and the taper portion 24 are formed so as to be inclined toward the kick-out side from the step-on side, the water on the tread side is tapered from the step-down side toward the kick-out side. 22 and the taper portion 24 smoothly flow into the groove, improving the wet hydroplaning performance.
In addition, by setting the width and length of the tapered portion 22 formed along the steeply inclined lug groove 18 optimally based on experiments and the like, the effect of improving drainage performance from the vicinity of the tire equatorial plane is exhibited. Can do.

  Further, a steeply inclined lug groove 18 and a first gently inclined lug groove 20 are formed in the land portion 16 between the circumferential main grooves 14, both of which cross the land portion 16. First, a land portion continuous in the circumferential direction is provided on the tire equator plane CL. And since this land part 16 has secured the groove wall strength by the taper part 22 while taking the area of the steeply inclined lug groove 18, it does not provide the circumferential direction main groove on the tire equatorial plane CL, but has drainage performance. At the same time, the braking performance and the handling stability can be ensured by improving the rigidity of the land portion 16 near the tire equatorial plane CL.

  When the pneumatic tire 10 travels on snow, the circumferential main groove 14, the steeply inclined lug groove 18, the first gently inclined lug groove 20, the second gently inclined lug groove 30, and the first Since the snow enters the three gently inclined lug grooves 32 and a strong snow column can be formed in the taper portion 22 and the taper portion 24, the land portion is caught by the snow column, and the running performance on snow can be improved.

Thereby, the pneumatic tire 10 of this embodiment was able to improve wet hydroplaning performance, block rigidity, and performance on snow.
In addition, by denting the central portion of each of the tapered portion 22 and the tapered portion 24, an effective edge effect can be obtained when running on snow, and at the same time, a strong snow column can be formed in the groove, Improvements in snow performance are being achieved.

(Test example)
In order to confirm the effect of the present invention, a tire of a conventional example, two types of tires of a comparative example, and a tire of an example to which the present invention is applied are prepared, wet hydroplaning performance, wet braking performance, dry braking performance, We compared wet steering stability performance, dry steering stability performance, snow handling stability performance, snow traction performance, and snow braking performance on a real vehicle.

Example tire: The tire described in the above embodiment.
Conventional tire: a tire having a tread pattern shown in FIG. 3, reference numerals 100 and 102 denote circumferential main grooves, reference numerals 104, 108, and 110 denote lug grooves, reference numeral 106 denotes a narrow groove, reference numeral 110 denotes a sipe, and reference numeral 112E denotes a grounding end. The inclined lug groove 104 has a groove width of 5 to 6 mm, a groove angle of 45 °, and a groove depth of 9 mm.
Tire of Comparative Example 1: A tire obtained by removing the tapered portion 22 on the steeply inclined lug groove side from the tire of the example (see FIG. 4).
Tire of Comparative Example 2: A tire obtained by removing the tapered portion 24 from the tire of the example (see FIG. 5).
In the examples, the groove width of the steeply inclined lug groove is 4 to 8 mm (8 mm is a value including the width of the tapered portion), and the groove angle is 70 ° with respect to the tire circumferential direction (one on the circumferential main groove side). The groove depth is 8 mm.

The test method and evaluation method will be described below.
-Wet hydroplaning performance (straight forward): Feeling evaluation at the hydroplaning limit speed when passing straight on a wet road surface with a water depth of 5 mm. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the wet hydroplaning performance.

-Wet braking performance: A braking distance was measured when full braking was performed from a traveling state on a straight road surface with a water depth of 2 mm at a speed of 80 km / h. The evaluation is represented by an index with the reciprocal of the braking distance of the conventional example being 100, and the larger the value, the better the wet braking performance.

Dry braking performance: A braking distance was measured when full braking was performed from a traveling state on a dry straight road surface at a speed of 80 km / h. The evaluation is expressed as an index with the reciprocal of the braking distance of the conventional example being 100, and the larger the value, the better the dry braking performance.

-Wet maneuvering stability: Test driver's feeling evaluation when driving on a wet circuit course in various driving modes. The evaluation is expressed as an index with the conventional example being 100, and the larger the numerical value, the better the wet steering stability.

・ Dry maneuvering stability performance: Test driver's feeling evaluation when driving on a dry circuit course in various driving modes. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the dry steering stability.

・ Snow maneuvering stability performance: Comprehensive feeling evaluation of braking performance, startability, straightness, and cornering performance on a test course on a snowy road surface. The evaluation is expressed as an index with the conventional example being 100, and the larger the value, the better the steering stability on snow.

-Snow traction performance: Time until acceleration on snow from 10 km / h to 45 km / h was measured. The evaluation is an index display in which the reciprocal of the acceleration time of the conventional example is 100, and the larger the value, the better the snow traction performance.

Snow braking performance: The braking distance was measured when the vehicle was fully braked from the running state on the snow at a speed of 40 km / h. The evaluation is an index display in which the reciprocal of the braking distance of the conventional example is 100, and the larger the value, the better the braking performance on snow.

  In the test, the tire size was 225 / 45R17 (tread width 177 mm), the internal pressure was 220 kPa, and the load was equivalent to two passengers in an actual vehicle.

試験の結果、本発明の適用された実施例のタイヤは、従来例、及び比較例よりも全ての項目で性能が向上していることが分かった。

As a result of the test, it was found that the performance of the tire of the example to which the present invention was applied was improved in all items as compared with the conventional example and the comparative example.

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Tread 14 Center side circumferential main groove 16 Shoulder side circumferential main groove 18 Center rib (land part)
22 1st inclined lug groove 24 2nd inclined lug groove 26 3rd inclined lug groove 28 1st block (land part)
30 Second block (Land)
32 3rd block (Land)
34 1st slope land part 34A edge 34B edge 50 2nd slope land part

Claims (2)

A tread that touches the road surface,
A plurality of circumferential main grooves disposed on both sides of the tire equatorial plane of the tread and extending along the tire circumferential direction;
Provided on the tread and extending from the circumferential main groove closest to the tire equatorial plane toward the tire equatorial plane and terminating in the land, and the end on the tire equatorial plane side is ahead of the end on the outer side in the tire axial direction A plurality of inclined lug grooves that are inclined with respect to the tire axial direction so as to contact the ground,
Formed at the edge of the inclined lug groove side of the land portion of the tread and the edge of the circumferential main groove side, and inclines toward the groove side and narrows from the stepping side toward the kicking side. Taper part,
A land portion provided on the tire equatorial plane of the tread and continuous in the tire circumferential direction;
Pneumatic tire having   The pneumatic tire according to claim 1, wherein when the tapered portion is viewed in a cross section along the groove width direction, a center portion of the contour shape of the tapered portion is recessed.

Images