JP5417253B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire.

  Conventionally, for example, as shown in Patent Document 1 below, on the outer circumferential surface of a tread portion, the tire rotation direction when the vehicle moves forward gradually from the center portion in the tire width direction toward the outer end portion in the tire width direction. A pneumatic tire is known in which a plurality of inclined grooves extending toward the front side are formed at intervals in the tire circumferential direction.

JP 2000-318411 A

  However, the conventional pneumatic tire has room for improvement in terms of pitch noise reduction and drainage performance improvement.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a pneumatic tire capable of both reducing pitch noise and improving drainage performance.

  In order to solve the above-described problems and achieve such an object, the pneumatic tire of the present invention has a tire rotation direction when the vehicle moves forward, and a tire width direction on the outer peripheral surface of the tread portion. A pneumatic tire in which a plurality of inclined grooves extending toward the front side in the tire rotation direction are formed at intervals in the tire circumferential direction, gradually from the center of the tire toward the outer end in the tire width direction. On the bottom wall surface of the groove, a fine land portion extending along the inclined groove is projected, and the protruding height of the outer end portion located at the outer end portion in the tire width direction of the inclined groove in the narrow land portion is: In the narrow land portion, the protruding height of the inner end portion located at the inner end portion in the tire width direction of the inclined groove is lower than the depth of the inclined groove.

According to the present invention, since the narrow land portion extending along the inclined groove protrudes from the bottom wall surface of the inclined groove, the inner volume of the inclined groove is suppressed, and the air column resonance sound generated in the inclined groove is reduced. Sound pressure energy can be suppressed, and pitch noise can be reduced.
Further, in the narrow land portion, since the protruding height of the inner end portion is higher than the protruding height of the outer end portion, the tire equator portion having a relatively slow flow rate during drainage out of the water in the inclined groove. While it becomes possible to easily guide the nearby water to the flow along the inclined groove, the protruding height of the outer end portion of the narrow land portion is the protruding height of the inner end portion of the narrow land portion, And since it is lower than the depth of the inclined groove, it is possible to prevent the fine land portion from obstructing the flow of water at the outer end in the tire width direction where the flow velocity during drainage is relatively high in the inclined groove. Thus, drainage performance can be improved with certainty.

  Here, the protruding height of the inner end portion of the narrow land portion may be equal to or greater than the depth of the inclined groove.

  In this case, the protruding height of the inner end portion of the narrow land portion is equal to or greater than the depth of the inclined groove and constitutes a part of the outer peripheral surface of the tread portion. It becomes possible to reduce the difference between the compression stiffness in the tire radial direction of the block portion located between the inclined grooves adjacent in the circumferential direction and the compression stiffness in the tire radial direction of the portion where the inclined groove is located, Pitch noise can be more reliably reduced.

  In this configuration, the inclined groove may be curved so that an angle formed with the tire equator portion gradually increases from the inner side to the outer side in the tire width direction in a plan view of the tread portion.

In this case, since the inclined groove is curved as described above in a plan view of the tread portion, it becomes easy to guide water between the wet road surface to the outside in the tire width direction, and the drainage performance is further improved. be able to.
On the other hand, the block portion gradually decreases in length in the tire circumferential direction from the outer side in the tire width direction toward the inner side, and the contact pressure gradually increases accordingly.
However, as described above, since the inner end portion of the narrow land portion constitutes a part of the outer peripheral surface of the tread portion, the portion of the block portion located near the tire equator where the ground pressure increases. It becomes possible to suppress the contact pressure and improve the steering stability and uneven wear resistance.

  Further, the protruding height of the narrow land portion may gradually decrease from the inner side to the outer side in the tire width direction.

  In this case, since the protrusion height of the narrow land portion gradually decreases from the inner side to the outer side in the tire width direction, the water in the vicinity of the tire equator part of the water in the inclined groove is out of the effects described above. Thus, it is possible to ensure that the flow along the inclined groove is easily guided, and that the fine land portion inhibits the flow of water from being inhibited at the outer end of the inclined groove in the tire width direction.

  Further, at least a pair of circumferential grooves sandwiching the tire equator portion in the tire width direction is formed on the outer circumferential surface of the tread portion, and in the narrow land portion, the portion located at the intersection of the circumferential groove and the inclined groove The protruding height may be lower than the depth of the circumferential groove.

  In this case, since the protruding height of the portion located at the intersection in the narrow land portion is lower than the depth of the circumferential groove, the circumferential groove when this tire is new is provided by arranging the narrow land portion. It is possible to prevent the drainage performance of the water from being hindered.

  According to the pneumatic tire of the present invention, both pitch noise reduction and drainage performance can be improved.

It is a top view showing a part of tread part of a pneumatic tire shown as one embodiment concerning the present invention. It is AA arrow sectional drawing of the pneumatic tire shown in FIG. FIG. 3 is a cross-sectional view of the pneumatic tire shown in FIG. 1 taken along line BB. It is CC sectional view taken on the line of the pneumatic tire shown in FIG. It is a partial cross section figure of the pneumatic tire shown as other embodiments concerning the present invention. FIG. 6 is a partial cross-sectional view of a pneumatic tire shown as still another embodiment according to the present invention.

Hereinafter, an embodiment of a pneumatic tire according to the present invention will be described with reference to FIGS. 1 to 4.
In the pneumatic tire 1 of the present embodiment, the tire rotation direction when the vehicle moves forward is specified, and the tire is arranged on the outer peripheral surface of the tread portion 11 from the center portion in the tire width direction H as shown in FIG. A plurality of inclined grooves 12 extending gradually toward the front side F in the tire rotation direction are formed at intervals in the tire circumferential direction toward the outer end in the width direction H.
In the pneumatic tire 1 of the present embodiment, a known bead core, a carcass ply, a steel belt, and the like (not shown) are embedded. In addition, on the outer surface of the pneumatic tire 1, a not-shown explicit portion such as an arrow, which can specify the tire rotation direction when the mounted vehicle moves forward, is formed. The illustrated pneumatic tire 1 is attached to a vehicle so that the vehicle moves forward when the tread portion 11 rotates so as to move upward from the lower side of the page.

  The plurality of inclined grooves 12 are disposed on both sides of the outer circumferential surface of the tread portion 11 so as to sandwich the tire equator portion CL in the tire width direction H. Further, among the both side portions of the outer peripheral surface of the tread portion 11, a plurality of inclined grooves 12 disposed on one side in the tire width direction H and a plurality of inclined grooves disposed on the other side in the tire width direction H. 12 differs from the position along the tire circumferential direction. In each inclined groove 12, the inner end edge 12 a in the tire width direction H is located on the tire equator portion CL, and the outer end edge 12 b in the tire width direction H is the outer side in the tire width direction H on the outer peripheral surface of the tread portion 11. It is located on the edge 11a.

Further, in the present embodiment, each inclined groove 12 is curved so that the angle formed with the tire equator portion CL in the plan view of the tread portion 11 gradually increases from the inner side to the outer side in the tire width direction H. Thereby, in the outer peripheral surface of the tread portion 11, the block portion 11b located between the inclined grooves 12 adjacent in the tire circumferential direction gradually increases in length in the tire circumferential direction from the outside in the tire width direction H toward the inside. Is shorter.
In the illustrated example, the inclined groove 12 is extended so as to exhibit a convex curve toward the front side F in the tire rotation direction in a plan view of the tread portion 11. Note that the groove width of a portion of the inclined groove 12 located on the inner side in the tire width direction H with respect to the circumferential groove 13 described later is gradually narrowed from the outer side to the inner side in the tire width direction H. The depth of the inclined groove 12 is the same over the entire length.

  Furthermore, in the present embodiment, a pair of circumferential grooves 13 that sandwich the tire equator portion CL in the tire width direction H are formed on the outer peripheral surface of the tread portion 11. Each circumferential groove 13 is disposed at the center portion in the tire width direction H in each of the both side portions of the outer circumferential surface of the tread portion 11. Further, in each of the both side portions of the tread portion 11, the circumferential groove 13 penetrates the plurality of inclined grooves 12 in the tire circumferential direction, and the circumferential groove 13 and the plurality of inclined grooves 12 communicate with each other. Note that the depth of the circumferential groove 13 is equal to the depth of the inclined groove 12. Further, the width of the circumferential groove 13 is equal to the width of the outer end portion of the inclined groove 12 in the tire width direction H.

In the present embodiment, a narrow land portion 14 extending along the inclined groove 12 protrudes from the bottom wall surface 12 c of the inclined groove 12.
In the example shown in the drawing, the narrow land portion 14 is extended on the bottom wall surface 12 c of the inclined groove 12 over almost the entire length thereof. That is, in the narrow land portion 14, the inner end edge 14a in the tire width direction H is located slightly away from the inner end edge 12a in the tire width direction H of the inclined groove 12, and the outer end edge 14b in the tire width direction H is The inclined groove 12 is located on the outer edge 12b in the tire width direction H.

Further, as shown in FIG. 2 and FIG. 3, the protruding height of the outer end portion located at the outer end portion in the tire width direction H of the inclined groove 12 in the narrow land portion 14 is the inclined groove 12 in the narrow land portion 14. Is lower than the protruding height of the inner end portion located at the inner end portion in the tire width direction H and the depth of the inclined groove 12.
In the present embodiment, the protruding height of the inner end portion of the narrow land portion 14 is equal to or greater than the depth of the inclined groove 12. Thereby, the inner end portion of the narrow land portion 14 constitutes a part of the outer peripheral surface of the tread portion 11. In the illustrated example, the protruding height of the inner end portion of the narrow land portion 14 is equal to the depth of the inclined groove 12. The protruding height of the inner end portion of the narrow land portion 14 and the depth of the inclined groove 12 are each about 8 mm, for example, and the protruding height of the outer end portion of the narrow land portion 14 is about 5 mm, for example. It has become.

Further, the protruding height of the narrow land portion 14 is gradually lowered from the inner side to the outer side in the tire width direction H. In the present embodiment, as shown in FIG. 4, the upper end edge of the fine land portion 14 extends linearly in a sectional view of the tire 1 along the direction in which the inclined groove 12 extends. Further, in the narrow land portion 14, the protruding height of the portion located at the intersection of the circumferential groove 13 and the inclined groove 12 is lower than the depth of the circumferential groove 13. The protruding height is, for example, 50% or less of the depth of the circumferential groove 13.
Further, in the illustrated example, the portion of the narrow land portion 14 located on the inner side of the circumferential groove 13 in the tire width direction H gradually decreases in thickness from the outer side to the inner side in the tire width direction H.

As described above, according to the pneumatic tire 1 according to the present embodiment, since the narrow land portion 14 extending along the inclined groove 12 is provided on the bottom wall surface 12c of the inclined groove 12, the inclined groove 12 is provided. Therefore, the sound pressure energy of air column resonance generated in the inclined groove 12 can be suppressed, and pitch noise can be reduced.
Further, in the narrow land portion 14, the protruding height of the inner end portion is higher than the protruding height of the outer end portion, so that the tire has a relatively slow flow rate during drainage of the water in the inclined groove 12. While it becomes possible to easily guide the water in the vicinity of the equator portion CL to the flow along the inclined groove 12, the protruding height of the outer end portion of the narrow land portion 14 is such that the inner end of the narrow land portion 14 Since the protruding height of the portion and the depth of the inclined groove 12 are lower, the fine land portion 14 flows in the outer end portion in the tire width direction H where the flow velocity during drainage becomes relatively high in the inclined groove 12. Can be suppressed, and the drainage performance can be improved with certainty.

  Furthermore, in this embodiment, since the protruding height of the inner end portion of the narrow land portion 14 is equal to or greater than the depth of the inclined groove 12 and constitutes a part of the outer peripheral surface of the tread portion 11, the tread portion 11 on the outer peripheral surface of the tire radial direction of the block portion 11b located between the adjacent inclined grooves 12 in the tire circumferential direction, and the compression stiffness in the tire radial direction of the portion where the inclined groove 12 is located. The difference can be reduced, and the pitch noise can be further reliably reduced.

Further, since the inclined groove 12 is curved as described above in a plan view of the tread portion 11, it becomes easy to guide water between the wet road surface to the outside in the tire width direction H, and the drainage performance is further ensured. Can be improved.
On the other hand, the block portion 11b gradually decreases in length in the tire circumferential direction from the outside toward the inside in the tire width direction H, and the contact pressure gradually increases along with this, as described above, Since the inner end portion of the narrow land portion 14 constitutes a part of the outer peripheral surface of the tread portion 11, the contact pressure of the portion located near the tire equator portion CL where the contact pressure increases in the block portion 11b. Thus, it is possible to suppress the steering stability and uneven wear resistance.

Further, since the protruding height of the narrow land portion 14 gradually decreases from the inner side to the outer side in the tire width direction H, among the above-described effects, the vicinity of the tire equator CL of the water in the inclined groove 12 It is ensured that the water is easily guided to the flow along the inclined groove 12 and that the fine land portion 14 is prevented from obstructing the water flow at the outer end portion in the tire width direction H in the inclined groove 12. Can be successful.
Moreover, in the narrow land part 14, since the protrusion height of the part located in the cross | intersection part of the circumferential groove 13 and the inclined groove 12 is lower than the depth of the circumferential groove 13, the narrow land part 14 was arrange | positioned. Thus, it is possible to prevent the drainage performance of the circumferential groove 13 from being disturbed when the tire 1 is new.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, the circumferential groove 13 is formed on the outer peripheral surface of the tread portion 11, but the circumferential groove 13 may not be formed, and the number and arrangement positions of the circumferential grooves 13 are not limited to those in the above embodiment and are appropriately determined. It may be changed.
Further, in place of the embodiment, the inclined groove 12 is gradually extended linearly toward the front side F in the tire rotation direction from the inner side to the outer side in the tire width direction H, and in a plan view of the tread portion 11. The angle formed between the inclined groove 12 and the tire equator CL may be made equal over the entire length of the inclined groove 12. Further, the width and depth of the inclined groove 12 are not limited to the above embodiment, and may be changed as appropriate.

Furthermore, in the said embodiment, although the upper end edge of the narrow land part 14 showed the structure extended linearly in the cross sectional view of this tire 1 along the direction where the inclination groove | channel 12 extends, it replaces with this, for example, FIG. As shown in Fig. 2, it may be extended in a curved shape recessed inward in the tire radial direction, may be extended in a convex curved shape outward in the tire radial direction, and further in a wave shape You may change suitably, such as extending.
Moreover, you may form in the part located in the said cross | intersection part in the thin land part 14, the recessed part 14e which opens in the outer side of a tire radial direction and a tire circumferential direction as it is depressed below.
Further, the protruding height of the narrow land portion 14 is not limited to the above embodiment, and may be changed as appropriate.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the gist of the present invention, and the above-described modified examples may be appropriately combined.

Next, the verification test about the effect demonstrated above was implemented.
First, during this test, pneumatic tires of Examples and Comparative Examples were prepared.
As an example, the pneumatic tire 1 shown in FIGS. 1 to 4 was adopted, and as a comparative example, a pneumatic tire having no fine land portion 14 in the pneumatic tire 1 shown in FIGS. 1 to 4 was adopted.
Further, as the pneumatic tires of the examples and comparative examples, 225 / 45R17 summer tires were adopted, and the rim width was set to 7J-17.

Each of the pneumatic tires of the example and the comparative example was mounted on a sedan-type domestic vehicle, and an object having a load of 600 N other than the driver was put on the vehicle, and the internal pressure specified by the vehicle was applied to each pneumatic tire. In this state, the pitch noise was evaluated by the feeling of the driver when the vehicle was coasting at 60 km / h on the dry road of the test course.
Next, each vehicle described above was run on the wet road surface (water depth 8 mm) of the test course, and the running speed when the hydroplaning phenomenon occurred was measured to evaluate the drainage performance.
The evaluation of pitch noise and drainage performance is evaluated by an index with the comparative example being 100, and the larger the value, the more the pitch noise is reduced and the better drainage performance.

  The results are shown in Table 1.

  As a result, it was confirmed that the pneumatic tire 1 of the example can achieve both reduction of pitch noise and improvement of drainage performance as compared with the pneumatic tire of the comparative example.

  Both reduction of pitch noise and improvement of drainage performance can be achieved.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 11 Tread part 12 Inclined groove 12c Bottom wall surface 13 Circumferential groove 14 Thin land part CL Tire equatorial part F Front side H Tire width direction

Claims (5)

The direction of tire rotation when the vehicle moves forward is specified, and gradually toward the front side in the tire rotation direction from the center in the tire width direction toward the outer end in the tire width direction on the outer circumferential surface of the tread portion. A pneumatic tire in which a plurality of inclined grooves extending in the tire circumferential direction are formed at intervals,
On the bottom wall surface of the inclined groove, a narrow land portion extending along the inclined groove is projected,
The protruding height of the outer end portion located at the outer end portion in the tire width direction of the inclined groove in the narrow land portion is the inner end portion located at the inner end portion in the tire width direction of the inclined groove in the narrow land portion. The pneumatic tire is characterized by being lower than the protruding height of and the depth of the inclined groove. The pneumatic tire according to claim 1,
The pneumatic tire according to claim 1, wherein a protruding height of the inner end portion of the narrow land portion is equal to or greater than a depth of the inclined groove. The pneumatic tire according to claim 2,
The pneumatic tire according to claim 1, wherein the inclined groove is curved so that an angle formed with the tire equator portion gradually increases from the inner side to the outer side in the tire width direction in a plan view of the tread portion. The pneumatic tire according to any one of claims 1 to 3,
The pneumatic tire is characterized in that the protruding height of the narrow land portion gradually decreases from the inner side to the outer side in the tire width direction. The pneumatic tire according to any one of claims 1 to 4,
On the outer circumferential surface of the tread portion, at least a pair of circumferential grooves that sandwich the tire equator portion in the tire width direction is formed,
The pneumatic tire according to claim 1, wherein in the narrow land portion, a protruding height of a portion located at an intersection of the circumferential groove and the inclined groove is lower than a depth of the circumferential groove.

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