JPH11263104A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve efficiency in water drainage of a pneumatic tire with a block pattern, while retaining block rigidity. SOLUTION: The vicinity of the acute angle corner of a block 32 is provided with a straight slope face 36 whose height is reduced gradually as it goes toward the tip. An arc-shaped chamfered part 40 is formed between a tread face 38 and the slope face 36, and between the tread face 38 and the slope face 36 an arc-shaped chamfered part 44 is formed whose radius is R2 at the tread face 38 while the radius R2 becomes smaller as it goes toward the block tip. Accordingly, smoothness of flow is obtained in a groove around the acute angle corner of the block 32 so as to improve efficiency in drainage without further acuteness of the acute angle corner's angle α. No necessity of extreme acuteness on the acute angle corner's angle a eliminates rigidity lowering of the acute angle corner so as to prevent partial abrasion deterioration around the acute angle corner and steering stability lowering, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a block pattern, and more particularly, to a pneumatic tire having improved drainage efficiency while ensuring block rigidity.

[0002]

2. Description of the Related Art As shown in FIG. 10A, a plurality of circumferential grooves 106 and a tire width direction (arrow L direction and arrow R direction) are used as a block pattern for improving drainage efficiency when traveling on a wet road surface. Plural inclined grooves 10 inclined with respect to
A block pattern having a diamond-shaped block 100 demarcated by 8 is known.

Conventionally, it is known that the drainage efficiency increases when the angle α of the acute corner of the block 100 is made more acute.

[0004]

However, if the sharp corners of the block 100 are made more acute in order to improve the drainage efficiency, the rigidity of the distal end portion is reduced, and the distal end portion is twisted when grounded. There is a problem that, due to falling down, uneven wear becomes remarkable and steering stability is reduced.

The present invention has been made in view of the above circumstances, and has as its object to provide a pneumatic tire capable of improving drainage efficiency while ensuring block rigidity.

[0006]

The invention according to claim 1 is defined by a plurality of circumferential grooves extending along the tire circumferential direction and a plurality of inclined grooves extending in a direction inclined with respect to the tire width direction. A pneumatic tire having a plurality of blocks formed, wherein near the acute corner of the block, the height of the block gradually decreases toward the tip of the acute corner, and a contact portion between the tread surface and the groove wall surface. , And an arc-shaped chamfer having a center of curvature on the block side at each contact point between the circumferential groove and the inclined groove.

The operation of the pneumatic tire according to the first aspect will be described. In the pneumatic tire according to claim 1, the height of the block is gradually reduced near the acute corner of the block toward the tip of the acute corner, and the contact portion between the tread surface and the groove wall surface, and the circumferential direction. Since there is an arc-shaped chamfer having a center of curvature on the block side at the contact point between the groove and the inclined groove, the flow of water in the groove near the acute corner becomes smooth,
The drainage efficiency can be improved without further increasing the angle of the acute corner.

Further, since the angle of the acute corner does not have to be further acute in order to increase drainage efficiency, uneven wear near the acute corner does not deteriorate, and steering stability does not decrease. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, a tread 12 of a pneumatic tire 10 according to the present embodiment has a tire circumferential direction (arrow S).
Direction, and the circumferential grooves 14, 16, 18 extending along the direction opposite to the arrow S direction, and the inclined grooves 20, 22, 24, 26 inclined with respect to the tire width direction (arrow L, R directions). Blocks 28, 30, 32, and 34 are sectioned.

Here, the inclined grooves 20, 22 on the left side of the drawing incline to the left with respect to the tire equatorial plane CL, and the inclined grooves 24, 26 on the right side in the drawing with the tire equatorial plane CL as the boundary. It is inclined.

The pneumatic tire 10 has an arrow S in the drawing.
It is mounted on the vehicle to rotate in the direction indicated by the direction.

The angle α (intersection angle between the circumferential groove and the inclined groove) of the acute corner of the blocks 28, 30, 32, 34 when the tread 12 is viewed in a plan view is within the range of 20 ° to 75 °. Is set to

As shown in FIGS. 2 (A) and 2 (B), the vicinity of the sharp corner of the block 32 has a flat inclined surface 36 whose height H gradually decreases toward the tip, and the tread surface. An arc-shaped chamfered portion 40 having a radius R1 having a center of curvature is formed between the block 38 and the inclined surface 36 inside the block.

Further, between the inclined surface 36 and the block side wall surface 42, there is formed an arc-shaped chamfered portion 44 having a radius R2 at the portion of the tread surface 38 and decreasing the radius R2 toward the tip of the block. .

The other blocks 28, 30, and 34 also have inclined surfaces 36 near the sharp corners, similarly to the block 32, and an arc-shaped chamfered portion 4 is provided between the tread surface 38 and the inclined surface 36.
0 is formed, and an arc-shaped chamfered portion 44 is formed between the inclined surface 36 and the block side wall surface 42.

The arc-shaped chamfered portion 40 and the arc-shaped chamfered portion 44 are smoothly connected by a smooth arc curve.

In the pneumatic tire 10 of the present embodiment, an inclined surface 36 is provided near an acute corner of each of the blocks 28, 30, 32, and 34, and an arc-shaped chamfered portion is provided at a contact point between the tread surface 38 and the inclined surface 36. 40, and an arc-shaped chamfered portion 44 is formed between the inclined surface 36 and the block side wall surface 42, so that the water in the groove near the acute corner of each of the blocks 28, 30, 32, 34 is formed. The flow becomes smooth, and the drainage efficiency can be improved without making the angle α of the acute corner more acute.

For example, as shown in FIGS. 3A and 4A, in the block 100 in which the arc-shaped chamfer is not formed at the acute corner, the flow A of water in the groove is disturbed. 3
As shown in FIG. 4B and FIG. 4B, in the block 32 of the present embodiment (the same applies to blocks 28, 30, and 34), the flow A of water in the groove becomes smooth.

Further, since it is not necessary to make the angle α of the sharp corners of the blocks 28, 30, 32, 34 extremely sharp in order to make the flow of water smooth, the rigidity of the sharp corners is not reduced. In addition, there are no problems such as deterioration of uneven wear near the acute corner and deterioration of steering stability.

Here, in order to improve the drainage efficiency,
The radius R1 of the arc-shaped chamfered portion 40 is preferably set to 5 to 30 mm, and the radius R2 of the arc-shaped chamfered portion 44 (at the tread surface 38) is preferably set to 3 to 8 mm.

Note that, as shown in FIG.
A single arc-shaped chamfered portion 46 having a radius R3 may be formed at an acute corner (the same applies to 28, 30, and 34). The radius R3 has a maximum value on the tread 38 and decreases as it goes toward the tip.

The radius R3 of the arc-shaped chamfer 46 (the tread 38)
Is preferably set to 5 to 10 mm.

As shown in FIG. 6A, if a straight chamfer 104 which is not a circular arc is formed at an acute angle corner of the block 102, the straight line chamfer 104 is formed when the block 102 comes into contact with the road surface 48. The chamfer 104 hits at once, and the blow sound becomes loud.

On the other hand, a single arc-shaped chamfered portion 4 is formed at the acute corner.
When the block 6 is formed, as shown in FIG.
2 (similarly, 28, 30, and 34) touches the road surface 48 (when stepping on), because the arc-shaped chamfered portion 46 touches the road surface 48 and then touches the ground. The impact sound can be reduced, and the pattern noise can be reduced.

The sharp corners of the blocks 32 (the same applies to blocks 28, 30, and 34) may have a larger radius R1 of the arc-shaped chamfered portion 40 as shown in FIG. An inverted arc portion 50 having a center of curvature outside the block may be formed on the base side. (Test Example) A vehicle equipped with the tire according to the embodiment to which the present invention is applied and a vehicle equipped with a conventional tire are prepared. The vehicle was entered in steps and the lateral acceleration at each speed was measured. When the lateral acceleration becomes 0, the tire is completely lifted off the road surface.

The tire of the conventional example and the tire of the embodiment have the same pattern, but have different shapes at acute corners.

FIGS. 10A and 10B show a conventional tire.
As shown in FIG. 1, the tire has a block whose sharp corners are not chamfered at a constant height.

The tire of the embodiment is a tire having a block whose acute corners are shaped as shown in FIG. Incidentally, as shown in FIG. 5A, the radius R3 of the arc-shaped chamfered portion on the tread is 5 mm, and as shown in FIG. 5B, the radius R1 is 10 mm and the angle θ is 35 °.

The height H of the block of the tire of the conventional example and the example is 8.1 mm. As shown in the graph of FIG. 9, it can be seen that the pneumatic tire of the present invention has a higher lateral acceleration and less slippage than the conventional pneumatic tire. This is a proof that the tires of the examples are excellent in drainage.

[0031]

As described above, since the pneumatic tire of the present invention has the above-described structure, it is possible to improve drainage efficiency without deteriorating uneven wear and steering stability. It has an excellent effect.

[Brief description of the drawings]

FIG. 1 is a plan view of a tread of a pneumatic tire according to one embodiment of the present invention.

FIG. 2A is a perspective view of the vicinity of an acute corner of the block according to the embodiment, and FIG. 2B is a view 2 (B) -2 of FIG. 2A.
(B) It is a sectional view taken on a line.

FIG. 3A is an explanatory diagram showing a flow of water near a block where an arc-shaped chamfer is not formed, as viewed from obliquely above the block, and FIG. 3B is a diagram showing water near a block according to the embodiment; It is explanatory drawing which looked at the block which showed the flow from diagonally upper direction.

FIG. 4A is an explanatory view showing a flow of water near a block where an arc-shaped chamfer is not formed, as viewed from the side of the block; FIG. 4B is a flow of water near a block according to the embodiment; FIG. 4 is an explanatory diagram viewed from the side of the block.

5A is a perspective view of a block according to another embodiment, and FIG. 5B is a cross-sectional view taken along line 5 (B) -5 (B) of FIG. 5A.

FIG. 6A is a perspective view showing a state where a block having no arc-shaped chamfered portion abuts on a road surface;
(B) is a perspective view showing a state where the block formed with the arc-shaped chamfered portion comes into contact with the road surface.

FIG. 7 is a sectional view of a block according to still another embodiment.

FIG. 8 is a sectional view of a block according to still another embodiment.

FIG. 9 is a graph showing a relationship between a test tire speed and a lateral acceleration.

10A is a plan view of a tread of a conventional tire, and FIG. 10B is a plan view of 10 (B) -10 in FIG. 10A.
(B) It is a sectional view taken on a line.

[Explanation of symbols]

 Reference Signs List 10 Pneumatic tire 14 Circumferential groove 16 Circumferential groove 18 Circumferential groove 20 Inclined groove 22 Inclined groove 24 Inclined groove 26 Inclined groove 28 Block 30 Block 32 Block 34 Block 40 Arc chamfer 44 Arc chamfer 46 Arc chamfer Department

Claims (1)

[Claims] 1. A pneumatic tire having a plurality of blocks defined by a plurality of circumferential grooves extending along a tire circumferential direction and a plurality of inclined grooves extending in a direction inclined with respect to a tire width direction. In the vicinity of the sharp corner of the block, the height of the block gradually decreases toward the tip of the sharp corner, and at the contact portion between the tread and the groove wall surface, and at the contact portion between the circumferential groove and the inclined groove. A pneumatic tire having an arc-shaped chamfer having a center of curvature on each block side.