JP2015223916A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which has an improved on-snow performance while maintaining a wear resistant performance.SOLUTION: A pneumatic tire in which a tread part 2 is provided with a pair of shoulder major grooves 3 and shoulder land parts 10 which are continuously extended in a tire circumferential direction. Each shoulder land part 10 is provided with plural shoulder lug grooves 11 which are terminated in the shoulder land part 10, and a first shoulder siping 13 which communicates between inner end parts 12 of adjacent shoulder lug grooves 11. Between the first shoulder siping 13 and the shoulder major groove 3, a rib 15, which is continuously extended in the tire circumferential direction, is formed.

Description

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

  Patent Document 1 below proposes a pneumatic tire in which a plurality of lug grooves are provided in a shoulder land portion. Such a pneumatic tire suppresses uneven wear of the shoulder land portion while maintaining wet performance.

JP 2010-132181 A

  However, the pneumatic tire disclosed in Patent Document 1 has room for further improvement in terms of both noise performance and wet performance.

  The present invention has been devised in view of the actual situation as described above, and provides a pneumatic tire that achieves both noise performance and wet performance on the basis of improving the shape and the like of the shoulder land portion. The main purpose.

  The present invention provides a pneumatic tire in which a tread portion is provided with a pair of shoulder main grooves extending continuously in the tire circumferential direction on the tread ground end side, and a shoulder land portion on the outer side in the tire axial direction of each shoulder main groove. A plurality of shoulder lug grooves extending at least inward in the tire axial direction from the tread grounding end and terminating in the shoulder land portion, and the shoulder lug grooves adjacent to each other in the tire circumferential direction. A first shoulder sipe that communicates between the inner end portions in the tire axial direction is provided, and a rib extending continuously in the tire circumferential direction is provided between the first shoulder sipe and the shoulder main groove. It is characterized by being formed.

  In the pneumatic tire of the present invention, a second shoulder sipe that extends at least from the tread grounding end inward in the tire axial direction and terminates without communicating with the first shoulder sipe is provided between the shoulder lug grooves. It is desirable.

  In the pneumatic tire of the present invention, the shoulder lug groove has a groove width of 3.5 to 5.5 mm, and the first shoulder sipe and the second shoulder sipe have a width of 1.0 mm or less. Is desirable.

  In the pneumatic tire of the present invention, the shoulder main groove is provided in the tread portion by providing at least one center main groove extending continuously in the tire circumferential direction on the inner side in the tire axial direction than the shoulder main groove. And the middle land portion divided by the center main groove is provided on both sides of the tire equator, and each middle land portion has an inner side extending from the center main groove in the tire axial direction and terminating in the middle land portion. It is desirable that the middle lug groove and the outer middle lug groove extending inward in the tire axial direction from the shoulder main groove and terminating in the middle land portion are alternately provided.

  In the pneumatic tire according to the present invention, the inner middle lug groove is connected to the center main groove and extends incline with respect to the tire circumferential direction, and is connected to the tire axially outer side of the first part. It is desirable to include a second portion that is inclined at a larger angle than the first portion with respect to the circumferential direction.

  In the pneumatic tire according to the present invention, it is desirable that the outer middle lug grooves are provided without intersecting the projected areas in the tire axial direction of the shoulder lug grooves.

  The tread portion of the pneumatic tire of the present invention is provided with a pair of shoulder main grooves extending continuously in the tire circumferential direction on the most tread grounding end side, and a shoulder land portion on the outer side in the tire axial direction of each shoulder main groove. ing.

  Each shoulder land portion includes at least a plurality of shoulder lug grooves extending inward in the tire axial direction from the tread contact end and terminating in the shoulder land portion, and inner end portions in the tire axial direction of shoulder lug grooves adjacent in the tire circumferential direction. And a first shoulder sipe that communicates with each other. Such a shoulder lug groove effectively discharges water outward in the tire axial direction during wet running. In addition, since the inner end portion of the shoulder lug groove communicates with the first shoulder sipe, the pumping sound of the shoulder lug groove is suppressed.

  A rib extending continuously in the tire circumferential direction is formed between the first shoulder sipe and the shoulder main groove. Such a rib prevents noise generated by pumping the groove and the hitting sound of the land portion from occurring on the inner side in the tire axial direction, thereby improving noise performance.

  As described above, the pneumatic tire of the present invention can achieve both wet performance and noise performance.

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 shoulder land part and middle land part of FIG. (A) is BB sectional drawing of the inner side middle lug groove of FIG. 3, (b) is CC sectional drawing of the outer side middle lug groove 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.

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 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 this embodiment 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 distance in the tire axial direction between the tread ground contact Te and Te in the normal state is defined as the tread ground contact width TW.

  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. For example, only one center main groove 4 may be provided on the tire equator C. The center main groove 4 extends linearly, for example.

  The groove width W1 of the shoulder main groove 3 and the groove width W2 of the center main groove 4 are, for example, 4.5 to 6.5% of the tread grounding width TW. Such shoulder main grooves 3 and center main grooves 4 effectively drain water between the road surface and the tread portion 2 during wet running, and improve wet performance. In the present embodiment, the groove width W1 of the shoulder main groove 3 and the groove width W2 of the center main groove 4 are respectively constant, but are not limited to such an embodiment.

  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 includes a pair of shoulder land portions 10 provided on the outer side in the tire axial direction of the shoulder main grooves 3, and a pair of shoulder main grooves 3 and a center main groove 4. Middle land portions 20 and 20 and a center land portion 40 between the center main grooves 4 and 4 are provided.

  FIG. 3 shows an enlarged view of the shoulder land portion 10 and the middle land portion 20 on the right side of FIG. As shown in FIG. 3, the shoulder land portion 10 is provided with a plurality of shoulder lug grooves 11 and a first shoulder sipe 13.

  The shoulder lug groove 11 has an inner end portion 12 extending at least inward in the tire axial direction from the tread ground contact end Te and terminating in the shoulder land portion 10. Such a shoulder lug groove 11 effectively drains water under the tread portion 2 to the outside in the tire axial direction during wet running.

  The shoulder lug groove 11 is convex and curved on one side in the tire circumferential direction, for example. The shoulder lug groove 11 of the present embodiment has a linear shape with the inner end 12e along the tire circumferential direction. The groove width W3 of the shoulder lug groove 11 is, for example, 3.5 to 5.5 mm. Such a shoulder lug groove 11 exhibits excellent wet performance and wandering performance.

  The first shoulder sipe 13 communicates between the inner end portions 12 in the tire axial direction of the shoulder lug grooves 11 adjacent to each other in the tire circumferential direction. The first shoulder sipe 13 of the present embodiment extends, for example, linearly along the tire circumferential direction. The edge of the first shoulder sipe 13 and the inner end 12e of the shoulder lug groove 11 are continuous in the tire circumferential direction. In this specification, “sipe” means a cut having a width of 1.0 mm or less, and is distinguished from a drainage groove.

  The first shoulder sipe 13 can effectively release the pressure of air in the groove when the shoulder lug groove 11 is grounded. Therefore, the pumping sound of the shoulder lug groove 11 is suppressed.

  A rib 15 extending continuously in the tire circumferential direction is formed between the first shoulder sipe 13 and the shoulder main groove 3. Such a rib 15 prevents the pumping sound of the groove and the hitting sound of the land portion that are generated on the inner side in the tire axial direction from leaking from the tread end side, so that the noise performance is improved. Moreover, such ribs 15 maintain the rigidity of the shoulder land portion 10 and exhibit excellent steering stability. In order to make the above effect more reliable, it is desirable that the rib 15 is, for example, a plain rib not provided with a groove and a sipe.

  The width W5 of the rib 15 is preferably not less than 0.15 times, more preferably not less than 0.18 times, preferably not more than 0.25 times, more preferably not more than 0.22 times the width W4 of the shoulder land portion 10. It is. Such ribs 15 enhance noise performance and wet performance in a well-balanced manner. The rib 15 of this embodiment extends linearly with a substantially constant width.

  For example, a second shoulder sipe 14 is preferably provided between the shoulder lug grooves 11. The second shoulder sipe 14 extends, for example, at least from the tread ground end Te inward in the tire axial direction, and terminates without communicating with the first shoulder sipe 13. Such a second shoulder sipe 14 relaxes the rigidity of the shoulder land portion 10 on the tread grounding end Te side, and exhibits excellent wandering performance.

  Each middle land portion 20 is provided with inner middle lug grooves 21 and outer middle lug grooves 22 alternately in the tire circumferential direction. The inner middle lug groove 21 extends outward from the center main groove 4 in the tire axial direction and terminates in the middle land portion 20. The outer middle lug groove 22 extends inward in the tire axial direction from the shoulder main groove 3 and terminates in the middle land portion 20. Such an inner middle lug groove 21 and an outer middle lug groove 22 exhibit excellent wet performance while maintaining steering stability.

  The inner middle lug groove 21 extends with an inclination with respect to the tire circumferential direction. The inner middle lug groove 21 includes a first portion 23 that communicates with the center main groove 4 and a second portion 24 that is inclined at a larger angle than the first portion 23 with respect to the tire circumferential direction.

  The angle θ1 of the first portion 23 with respect to the tire circumferential direction is preferably 20 ° or more, more preferably 25 ° or more, preferably 45 ° or less, more preferably 40 ° or less. Such a first portion 23 guides the water in the center main groove 4 to the outer side in the tire axial direction during wet running, and improves the wet performance.

  From the same viewpoint, the length L1 of the first portion 23 in the tire axial direction is preferably 0.25 times or more, more preferably 0.35 times or more, preferably 0.35 times or more the width W6 of the middle land portion 20. 5 times or less, more preferably 0.4 times or less.

  The angle θ2 of the second portion 24 with respect to the tire circumferential direction is preferably 60 ° or more, more preferably 65 ° or more, preferably 80 ° or less, more preferably 75 ° or less. Such a second portion 24 maintains the rigidity of the middle land portion 20 in the tire axial direction, and exhibits excellent steering stability.

  FIG. 4A shows a BB cross-sectional view of the inner middle lug groove 21 of FIG. As shown in FIG. 4A, the inner middle lug groove 21 is preferably provided with a tie bar 26 in which the groove bottom of the inner end portion 25 in the tire axial direction is raised. Such a tie bar 26 effectively suppresses uneven wear near the inner end 25 of the inner middle lug groove 21.

  As shown in FIG. 3, the outer middle lug groove 22 is inclined in the same direction as the inner middle lug groove 21, for example. The angle θ3 of the outer middle lug groove 22 with respect to the tire circumferential direction is preferably 60 ° or more, more preferably 65 ° or more, preferably 80 ° or less, more preferably 75 ° or less. Such an outer middle lug groove 22 enhances wet performance while maintaining the rigidity of the middle land portion 20 in the tire axial direction.

  The outer middle lug groove 22 includes, for example, an inner end portion 28 in which an angle with respect to the tire circumferential direction is gradually decreased toward the inner side in the tire axial direction. Thereby, uneven wear near the inner end portion 28 is suppressed.

  FIG. 4B shows a cross-sectional view of the outer middle lug groove 22 of FIG. 3 taken along the line C-C. As shown in FIG. 4B, it is desirable that the groove depth d3 of the inner end portion 28 of the outer middle lug groove 22 gradually increases from the inner side toward the outer side in the tire axial direction, for example. Such an inner end portion 28 maintains the rigidity of the central portion of the middle land portion 20 and exhibits excellent steering stability.

  As shown in FIG. 3, each outer middle lug groove 22 is preferably provided without intersecting the projection region 29 in the tire axial direction of each shoulder lug groove 11. As a result, the ground contact timing between the outer middle lug groove 22 and the shoulder lug groove 11 is shifted, so that the pumping sound is turned into white noise.

  The middle land portion 20 is preferably provided with, for example, a middle concave portion 30 in which an edge 20a on the center main groove 4 side is recessed.

  FIG. 5 shows an enlarged perspective view of the middle recess 30. As shown in FIG. 4, the middle concave portion 30 is formed by denting the middle land portion 20 in a substantially tetrahedral space composed of four triangular surfaces. The middle recess 30 includes, for example, a middle recess bottom surface 31 and a middle recess side surface 32.

  It is desirable that the middle concave bottom surface 31 is smoothly connected to the tread surface 20s of the middle land portion 20, for example. The middle recess bottom surface 31 of the present embodiment is inclined with respect to the tread surface 20s, and the depth of the middle recess 30 is gradually increased toward the bottom of the middle recess.

  The middle recess side surface 32 is, for example, substantially perpendicular to the middle recess bottom surface 31 and extends along the tire radial direction. The middle concave side surface 32 is, for example, a flat surface or a curved surface that is gently curved.

  The middle concave portion 30 including the middle concave bottom surface 31 and the middle concave side surface 32 further improves the wet performance while suppressing the air column resonance sound of the center main groove 4 (shown in FIG. 3).

  As shown in FIG. 3, for example, a plurality of first middle sipes 33 and second middle sipes 34 are provided in the middle land portion 20 of the present embodiment. For example, the first middle sipe 33 communicates between the middle recess 30 and the inner end 25 of the outer middle lug groove 22. For example, the second middle sipe 34 extends from the shoulder main groove 3 in the tire axial direction and terminates in the middle land portion 20. Such first middle sipe 33 and second middle sipe 34 make the rigidity distribution of the middle land portion 20 uniform, and suppress uneven wear of the middle land portion 20.

  FIG. 6 shows an enlarged view of the center land portion 40. The center land portion 40 is, for example, a rib continuous in the tire circumferential direction. Such a center land portion 40 exhibits excellent steering stability.

  For example, a center sub-groove 41 is provided in the center land portion 40 of the present embodiment.

  For example, the center sub-groove 41 extends linearly continuously in the tire circumferential direction. The center sub-groove 41 of the present embodiment is provided on the tire equator C, for example. Such a center sub-groove 41 exhibits excellent wet performance while maintaining the rigidity of the center land portion 40.

  In the center land portion 40 of the present embodiment, center recesses 42 are spaced apart in the tire circumferential direction.

  FIG. 7 shows an enlarged perspective view of the center recess 42. As shown in FIG. 7, the center recess 42 is formed by recessing the edges 40 e and 40 e on both sides of the center land portion 40. For example, the center recess 42 has substantially the same shape as the middle recess 30 (shown in FIG. 5), and includes a center recess bottom surface 43 and a center recess side surface 44. Such a center recess 42 exhibits excellent wet performance while suppressing the generation of air column resonance in the center main groove 4 (shown in FIG. 3).

  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 of size 225 / 65R17 having the basic pattern of FIG. 1 was prototyped based on the specifications in Table 1. As a comparative example, a tire having no ribs on the shoulder portion was manufactured as a prototype. These tires were mounted on the following test vehicles, and wet performance and noise performance were tested. 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 of 5 mm depth and 20 m in length. 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.

<Noise performance>
The in-vehicle noise when traveling on the road noise measuring road (asphalt rough road) at a speed of 100 km / h with the test vehicle was measured under the following conditions. The evaluation is the reciprocal of the value of the in-vehicle noise, and is represented by an index with the value of Comparative Example 1 being 100. The larger the value, the lower the vehicle interior noise and the better.
Measurement method: Measure the sound pressure level of the peak value of air column resonance near the narrow band of 240 Hz with a microphone. Microphone position: Table 1 shows the test results of the driver's window side ear test.

  As a result of the test, it was confirmed that the pneumatic tire of the example achieved both wet performance and noise performance.

2 Tread part 3 Shoulder main groove 10 Shoulder land part 11 Shoulder lug groove
12 Inner end 13 First shoulder sipe
15 Ribs

Claims (6)

A pneumatic tire in which a tread portion is provided with a pair of shoulder main grooves extending continuously in the tire circumferential direction on the tread ground end side, and a shoulder land portion on the outer side in the tire axial direction of each shoulder main groove. ,
In each of the shoulder land portions,
A plurality of shoulder lug grooves extending at least inward in the tire axial direction from the tread ground contact end and terminating in the shoulder land portion;
A first shoulder sipe that communicates between inner end portions in the tire axial direction of the shoulder lug grooves adjacent in the tire circumferential direction;
A pneumatic tire characterized in that a rib extending continuously in the tire circumferential direction is formed between the first shoulder sipe and the shoulder main groove.   2. The pneumatic tire according to claim 1, wherein a second shoulder sipe is provided between the shoulder lug grooves, extending at least from the tread grounding end inward in the tire axial direction and terminating without communicating with the first shoulder sipe. tire. The shoulder lug groove has a groove width of 3.5 to 5.5 mm,
The pneumatic tire according to claim 2, wherein the first shoulder sipe and the second shoulder sipe have a width of 1.0 mm or less. The tread portion is provided with at least one center main groove continuously extending in the tire circumferential direction on the inner side in the tire axial direction than the shoulder main groove, so that the shoulder main groove and the center main groove are separated. The middle land part was provided on both sides of the tire equator,
Each middle land portion includes an inner middle lug groove extending outward in the tire axial direction from the center main groove and terminating in the middle land portion, and extending inward in the tire axial direction from the shoulder main groove and terminating in the middle land portion. The pneumatic tire according to any one of claims 1 to 3, wherein outer middle lug grooves are alternately provided. The inner middle lug groove is
A first portion communicating with the center main groove and extending with respect to the tire circumferential direction;
The pneumatic tire according to claim 4, further comprising: a second portion that is connected to an outer side in the tire axial direction of the first portion and is inclined at an angle larger than the first portion with respect to a tire circumferential direction.   6. The pneumatic tire according to claim 4, wherein each outer middle lug groove is provided without intersecting a projection region in the tire axial direction of each shoulder lug groove.

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