JP2014094645A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep or improve hydro-planing resistance while reducing column resonance sound generated in a circumferential main groove extending in a circumferential direction.SOLUTION: A pneumatic tire 1 having a circumferential main groove 12B and a lag groove 16B extending from the circumferential main groove to the outside in a tire width direction, is provided with at least two projections 22 projecting from a groove bottom and separated from each other, near an intersecting portion 20 where the circumferential main groove and the lug groove intersect. A passage 24 is formed between the adjacent projections. In the passage, an inlet opening 24En on a far side from the lug groove and an outlet opening 24Ex on a close side to the lug groove are defined, and a cross-section of the inlet opening is larger than a cross-section of the outlet opening.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire for a passenger car.

  A pneumatic tire in which a plate-like protrusion is formed inside a circumferential main groove extending in the circumferential direction of the pneumatic tire is known (see Patent Document 1 as an example). By forming such a protrusion in the circumferential main groove, the generation of air column resonance due to the natural vibration of the air in the circumferential main groove excited by the vibration of the tread portion of the pneumatic tire, etc. Can be suppressed.

JP 2012-116339 A

  However, if a plate-like protrusion or the like as shown in Patent Document 1 is provided inside the circumferential main groove, the draining ability of the circumferential main groove may be impaired, thereby reducing the hydroplaning resistance. There is.

  Accordingly, an object of the present invention is to provide a pneumatic tire in which anti-hydroplaning performance is maintained or improved while reducing air column resonance generated in a circumferential main groove extending in the circumferential direction.

In order to solve the above problems, according to the present invention,
In a pneumatic tire having a circumferential main groove and a lug groove extending outward in the tire width direction from the circumferential main groove,
In the vicinity of the intersection where the circumferential main groove and the lug groove intersect, at least two protrusions protruding from the groove bottom and spaced apart from each other are provided,
A passage is formed between the protrusions adjacent to each other;
In the passage, an inlet opening on the side far from the lug groove and an outlet opening on the side near the lug groove are defined,
A cross-sectional area of the inlet opening is larger than a cross-sectional area of the outlet opening;
A pneumatic tire is provided.

  ADVANTAGE OF THE INVENTION According to this invention, hydroplaning performance can be maintained or improved, reducing the air column resonance generated in the circumferential main groove extending in the circumferential direction.

It is a plane development view showing a part of a tread part of a pneumatic tire concerning an embodiment of the present invention. It is a plane overhead view enlarged view in the A section of FIG. It is a plane enlarged line figure in the A section of FIG. FIG. 3 is a plan view enlarged view similar to FIG. 2, showing a first modification of the protrusion provided on the pneumatic tire according to the embodiment of the present invention. It is a plane overhead view similar to FIG. 2 which shows the 2nd modification of the protrusion provided in the pneumatic tire which concerns on embodiment of this invention. The plane overhead view similar to FIG. 2 which shows the shape of the processus | protrusion formed in the test tire of the comparative example 3. FIG. The plane overhead view similar to FIG. 2 which shows the shape of the processus | protrusion formed in the test tire of the comparative example 4. FIG.

  The invention will be described in more detail with reference to the above-mentioned drawings. It should be noted that the drawings are merely examples, and in order to facilitate the understanding of the present invention and to simplify the description of the drawings, the actual size, thickness, angle, number, scale, Note that it may not be the same as the shape.

(Embodiment)
FIG. 1 is a developed plan view showing a part of a tread portion 10 of a pneumatic tire 1 according to an embodiment of the present invention. In FIG. 1, the rotation direction of the pneumatic tire 1 is defined as the downward direction of FIG. Accordingly, when the pneumatic tire 1 is grounded and rolled, the grounding step on the grounding surface is the downward direction in FIG. 1, and conversely, the grounding kicking side is the upward direction in FIG. 1 is the tire width direction, and the side away from the tire width direction center line CL in the tire width direction is defined as the tire width direction outside, and the approaching side is defined as the tire width inside.

  The tread portion 10 of the pneumatic tire 1 according to the embodiment includes four circumferential main grooves 12A and 12B and four circumferential narrow grooves 14A and 14B that continuously extend in the circumferential direction, and a direction that crosses these. A plurality of lug grooves 16A and 16B and a sipe 18 are formed. The tread portion 10 has a so-called symmetrical pattern.

  In the pneumatic tire 1 according to the embodiment, the groove from the groove bottom to the intersecting portion 20 where the circumferential main groove 12B and the lug groove 16B extending outward in the tire width direction from the circumferential main groove 12B intersect. Two protrusions 22 projecting substantially perpendicular to the bottom surface and spaced apart from each other are provided. Further, in this embodiment, these protrusions 22 are formed integrally with the tread portion 10 from the rubber material of the tread portion 10.

  FIG. 2 is an enlarged plan view of the plane A in FIG. Referring to FIG. 2, it can be understood that a passage 24 is formed between the surfaces 22 </ b> S of the protrusion 22 facing each other by the protrusion 22. In the passage 24, an inlet opening 24En is provided at an end on the inner side in the tire width direction, that is, on the side far from the lug groove 16B, and an outlet opening 24Ex is provided at an end on the outer side in the tire width direction, that is, near the lug groove 16B. Defined.

  By providing such protrusions 22, when the pneumatic tire 1 of the embodiment is grounded and rolls on a wet road, the water flowing from the grounding stepping side to the grounding kicking side is indicated by the arrow in FIG. It will flow in the direction of pointing.

  FIG. 3 is an enlarged front view of a portion A in FIG. Here, the definition of the inlet opening 24En and the outlet opening 24Ex will be described with reference to FIG. First, a virtual surface 22Sim is created at a position intermediate between the surfaces 22S facing each other. At this time, the inlet opening 24En is a cross section of a passage that goes straight to the virtual surface 22Sim at the position of the inlet side end portion 22eEn of the protrusion 22, and the outlet opening 24Ex goes straight to the virtual surface 22Sim at the outlet side end portion 22eEx of the protrusion. It is a cross section of a passage.

  In the pneumatic tire 1 according to the embodiment, the cross-sectional area of the inlet opening 24En is formed to be larger than the cross-sectional area of the outlet opening 24Ex. Thereby, the flow rate of water when discharged from the outlet opening 24Ex becomes faster than the flow rate of water when the water flowing through the circumferential main groove 12B is introduced into the inlet opening 24En. This is due to a phenomenon in which the cross-sectional area is narrowed to increase the flow velocity. As described above, the water discharged from the outlet opening 24Ex is caused to flow toward the lug groove 16B at an increased flow velocity, so that a smooth water flow can be created. As a result, the hydroplaning performance can be improved. For this reason, in order to exhibit the drainage effect, the protrusion 22 is installed in the vicinity of the intersection 20.

  In the pneumatic tire 1 according to the embodiment, the outlet opening 24Ex of the passage 24 is disposed at the intersection 20 described above. Thereby, the water discharged from the outlet opening 24Ex is likely to flow toward the lug groove 16B. Therefore, the anti-hydroplaning performance can be improved. However, the outlet opening 24Ex may not be disposed in the above-described intersection 20.

  Referring to FIG. 3, in the pneumatic tire 1 of the present embodiment, the groove communication portion 26 which is a portion where the circumferential main groove 12 </ b> B and the lug groove 16 </ b> B communicate with each other on the normal direction extension 25 of the outlet opening 24 </ b> Ex. Can be understood. Thereby, the water which flowed along the channel | path 24 is discharged | emitted from the exit opening 24Ex, and is flowed toward the groove | channel communication part 26 and by extension, the lug groove 16B. Therefore, the anti-hydroplaning performance can be improved. However, the groove communication portion 26 may not be formed on the normal direction extension 25 of the outlet opening 24Ex.

  Further, the protrusion height of the protrusion 22 from the groove bottom is determined by the depth of the circumferential main groove 12B from the height of the wear indicator (protrusion provided on the groove bottom of the circumferential main groove to inform the wear limit). It is preferable that it is between up to half. When the protrusion height of the protrusion 22 is lower than the wear indicator, the vibration of the air in the circumferential main groove 12B is not affected, and the air column resonance noise cannot be reduced. On the other hand, when the protrusion height of the protrusion 22 is higher than half of the depth of the circumferential main groove, the flow of water along the circumferential main groove 12B is excessively inhibited, and consequently the hydroplaning resistance is lowered. Because there is a fear.

  In the pneumatic tire 1 according to the embodiment, as illustrated in FIG. 1, the entrance of the passage 24 formed in the circumferential main groove 12 </ b> B located on the right side of the tire width direction center line CL of the tread portion 10. The opening 24En faces the grounding step. Thereby, when the pneumatic tire 1 according to the embodiment rolls in contact with the wet road, the water flow from the grounding stepping side inside the circumferential main groove 12B is introduced from the inlet opening 24En without hindering. Then, it can pass through the passage 24 and be discharged from the outlet opening 24Ex. Thus, it is preferable that at least a part of the passage 24 is formed so as to face the grounding step.

  On the other hand, in the pneumatic tire 1 of the embodiment, the inlet opening 24En of the passage 24 formed in the circumferential main groove 12B located on the left side of the tire width direction center line CL of the tread portion 10 is on the grounding side. Facing. However, when the pneumatic tire is rotated and the direction of rotation of the tire is reversed, these inlet openings 24En face the grounding step. As described above, when the inlet opening 24En faces the right and left sides of the tire width direction center line CL, the hydroplaning performance is not changed even when the rotation direction of the pneumatic tire is reversed. There is an advantage.

  Further, when the present invention is applied to the rotation direction designation tire and the outlet openings 24Ex of all the passages 24 are directed to the grounding stepping side, the hydroplaning performance is further improved.

  In the pneumatic tire 1 according to the embodiment, the protrusion 22 does not contact the groove wall 12W of the circumferential main groove 12B even under a load condition. Therefore, unlike the pneumatic tire in which the protrusion is in contact with the groove wall of the circumferential main groove, it is possible to ensure the flow of water along the circumferential main groove 12B (see the arrow located on the left side of FIG. 2). As a result, the hydroplaning resistance can be improved.

  In summary, according to the pneumatic tire 1 of the embodiment, the following operational effects can be achieved.

(1) Since the protrusion 22 is provided in the circumferential main groove 12B extending in the circumferential direction, the natural vibration of air in the circumferential main groove 12B is prevented, thereby reducing air column resonance noise.
(2) Furthermore, in the pneumatic tire 1 according to the present embodiment, since the protrusions 22 are provided at the intersecting portion 20 with the shape as described above, the hydroplaning resistance can be maintained or improved.

  In the above embodiment, the protrusion 22 is provided only in the circumferential main groove 12B. However, the protrusion 22 may be provided in the circumferential main groove 12A, or may be provided in all the circumferential main grooves 12A and 12B. Good. Furthermore, in the present invention, the tread pattern of the tread portion 10 is not limited to that shown in FIG. As long as the pneumatic tire has a circumferential main groove extending in the circumferential direction and a lug groove extending outward in the tire width direction from the circumferential main groove, any pneumatic tire having any tread pattern is used. The present invention can be applied.

(First modification)
FIG. 4 shows a first modification of the protrusion 22 provided on the pneumatic tire 1 of the present embodiment. The present invention does not limit the shape of the protrusion 22 itself, and the shape of the protrusion 22 may be as shown in FIG. 4 or may be other shapes.

(Second modification)
FIG. 5 shows a second modification of the protrusion 22 provided on the pneumatic tire 1 of the present embodiment. In the second modification, three protrusions 22 are provided in the vicinity of one intersection 20, and the passages 24 are formed between the adjacent protrusions 22. In this case, two passages 24 are formed. Will be. Also in the second modification, each passage 24 is formed in the same manner as the passage 24 described in the above embodiment.

  Thus, in the present invention, the number of protrusions 22 is not limited, and four or more protrusions 22 may be formed at one intersection 20.

  Hereinafter, the present invention will be described in more detail with reference to examples.

  A pneumatic tire with a tire size of 205 / 55R16 91V was assembled on an aluminum wheel with a size of 16 × 6.5J, filled with air pressure of 230 kPa, and mounted on a 2000 cc front-wheel drive sedan type test vehicle, and the following tests were performed. .

[Pattern noise performance]
The vehicle interior sound was measured in the full frequency band (OA) on the driver's seat window side while traveling at 80 km / h, and the ratio of the sound pressure energy between the conventional example and other test tires at this time was taken. At this time, the conventional example is set to 100, and the larger the value, the smaller the volume and the better.

[Hydroplaning resistance]
Hydroplaning cornering measurement was performed at 100R at a speed of 100 km / h in a pool with a water depth of 10 mm, and the performance was measured from the size of the lateral G at that time. The conventional example is 100, which indicates that the larger the value, the better the performance.

  The configuration of the test tire used in these tests is as follows. In the test tires used for these performance tests, the tread pattern shown in FIG.

(Conventional example)
The test tire according to the conventional example is a reference tire, and is a reference tire in which the protrusion 22 is not formed in the circumferential main groove 12B.

(Examples 1-6)
In the test tires according to Examples 1 to 6, the protrusions 22 having the arrangement and shape described in the embodiment shown in FIG. 2 are formed, and the height of the protrusions 22 is set to the circumferential main groove. This is changed by 10% up to 10-60% of the groove depth. Since the groove depth of the circumferential main groove of each test tire is 8 mm, 20% of the groove depth of the circumferential main groove corresponding to the height of the protrusion 22 in Example 5 is the wear indicator of the test tire. Corresponds to a height of 1.6 mm.

(Comparative Example 1)
Unlike the protrusion 22 shown in FIG. 2, the test tire according to Comparative Example 1 has a smaller cross-sectional area of the inlet opening 24En than the cross-sectional area of the outlet opening 24Ex, like the protrusion shown in FIG. This is a test tire. In addition, the protrusion height of the protrusion 22 is 30% of the circumferential main groove depth.

(Comparative Example 2)
Unlike the protrusion 22 shown in FIG. 2, the test tire according to Comparative Example 2 is a test in which the outlet opening 24Ex is positioned on the grounding kicking side with respect to the intersection 20 as shown in FIG. Tire. In addition, the protrusion height of the protrusion 22 is 30% of the circumferential main groove depth.

  The results of the above test using the above test tire are shown below.

  According to the test results in Table 1, the test tires according to Examples 1 to 6 have reduced pattern noise and maintained or improved hydroplaning performance compared to the test tires according to the conventional examples. Understandable. In particular, when Example 4, Comparative Example 1 and Comparative Example 2 are compared, it can be understood that the shape of the protrusion 22 according to the present invention (FIG. 2) improves the hydroplaning performance.

  It should be noted that all features that can be understood by those skilled in the art from the specification, drawings, and claims are described as a combination of these features only in relation to certain other features. Unless otherwise expressly excluded, or unless the technical aspects are impossible or meaningless combinations, independently and in addition to other features or features disclosed herein. And can be combined in any combination.

  The present invention is defined as follows.

(1) In a pneumatic tire having a circumferential main groove and a lug groove extending outward in the tire width direction from the circumferential main groove,
In the vicinity of the intersection where the circumferential main groove and the lug groove intersect, at least two protrusions protruding from the groove bottom and spaced apart from each other are provided,
A passage is formed between the protrusions adjacent to each other;
In the passage, an inlet opening on the side far from the lug groove and an outlet opening on the side near the lug groove are defined,
A cross-sectional area of the inlet opening is larger than a cross-sectional area of the outlet opening;
Pneumatic tire.

(2) The protrusion height of the protrusion is from the height of the wear indicator of the pneumatic tire to half the depth of the circumferential main groove.
The pneumatic tire according to (1).

(3) The outlet opening of the passage is arranged in the intersection.
The pneumatic tire according to (1) or (2).

(4) A groove communication portion that is a portion where the lug groove communicates with the circumferential main groove is formed on a normal direction extension of a section of the outlet opening of the passage.
The pneumatic tire according to (1) or (2).

(5) The protrusion does not contact the groove wall of the circumferential main groove.
The pneumatic tire according to any one of (1) to (4).

(6) At least a part of the passage is formed so that the entrance opening faces the ground stepping side when the pneumatic tire is grounded and rolled.
The pneumatic tire according to any one of (1) to (5).

  The pneumatic tire of the present invention can be suitably used particularly as a passenger car tire.

12B circumferential direction main groove 16B lug groove 20 intersection 22 protrusion 24 passage 24En inlet opening 24Ex outlet opening

Claims (6)

In a pneumatic tire having a circumferential main groove and a lug groove extending outward in the tire width direction from the circumferential main groove,
In the vicinity of the intersection where the circumferential main groove and the lug groove intersect, at least two protrusions protruding from the groove bottom and spaced apart from each other are provided,
A passage is formed between the protrusions adjacent to each other;
In the passage, an inlet opening on the side far from the lug groove and an outlet opening on the side near the lug groove are defined,
A cross-sectional area of the inlet opening is larger than a cross-sectional area of the outlet opening;
Pneumatic tire. The protrusion height of the protrusion is from the height of the wear indicator of the pneumatic tire to half the depth of the circumferential main groove.
The pneumatic tire according to claim 1. The exit opening of the passage is disposed in the intersection.
The pneumatic tire according to claim 1 or 2. A groove communication portion, which is a portion where the lug groove communicates with the circumferential main groove, is formed on a normal direction extension of a section of the outlet opening of the passage.
The pneumatic tire according to claim 1 or 2. The protrusion does not contact the groove wall of the circumferential main groove;
The pneumatic tire according to any one of claims 1 to 4. At least a part of the passage is formed so that the inlet opening faces the ground stepping side when the pneumatic tire is grounded and rolls.
The pneumatic tire according to any one of claims 1 to 5.

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