JPH092019A - Pneumatic tire provided with directional high slant groove - Google Patents

Abstract

PURPOSE: To prevent wear by setting the angle of a groove side wall grounding later at normal rotation of a tire larger than the angle of that grounding earlier, in the angles of groove side walls of a directional high slant groove, in the tread outside territories from specified positions between the pattern center to both ends of a tread to both ends of the tread. CONSTITUTION: In the angles of groove side walls against a tread normal line N in the section perpendicular to the extending direction of the groove of a directional high slant groove 2, in tread outside territories S from the positions of 50% distance between the pattern center to both ends of the tread to both ends of the tread, the angle α of the groove side wall on the later grounding side at normal rotation of a tire is set to be 25 degrees for example, and the angle β of the groove side wall on the earlier grounding side at normal rotation of the tire is set to be 0 degree for example. Because the angle α of the groove side wall later grounding at normal rotation of the tire is larger than the angle βof the groove side wall earlier grounding in this way, rigidity of the corner part on the treading-in side of a block is weakened, and hence impact force at collision with the road surface is lightened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a left and right side of a pattern center with a relatively large inclination angle of 45 to 90 degrees, preferably 60 to 80 degrees with respect to the circumferential direction. The present invention relates to a pneumatic tire having a tread pattern in which a large number of directional highly inclined grooves extending in a V shape are arranged at intervals in the tire circumferential direction.

In the present specification, a "directionally inclined groove" is a groove extending obliquely with respect to the circumferential direction, and a portion of the groove extending obliquely near the equatorial plane of the tire is grounded first. , A groove in which a so-called directional tread pattern is formed, in which the direction of rotation (normal direction) of the tire when it is mounted on a vehicle is specified so that the side farther from the equatorial plane will come into contact with the ground later, The "outer region" is the pattern
It refers to the area from about 50% of the distance from the center to both ends of the tread to both ends of the tread, and the "tread inner area" means about 50% of the distance from the pattern center to both ends of the tread to the inside of the tread. Refers to the region, the "groove sidewall angle" refers to the angle of the groove sidewall with respect to the tread normal in the cross section perpendicular to the direction in which the groove extends, and "the stepping side of the block" refers to one of the blocks of the tire. Refers to the side to be grounded first during normal rotation,
The “block kick-out side” refers to the side of one block that comes into contact with the ground later when the tire rotates normally.

[0003]

2. Description of the Related Art A tread in which a large number of directional high-inclination grooves extending in a V shape at a relatively large inclination angle with respect to the circumferential direction sandwiching a pattern center are arranged at intervals in the tire circumferential direction. -In the conventional pneumatic tire having the pattern, the groove side wall angle on the kick-out side and the groove side wall angle on the stepping side of the directional high-inclination groove were the same.

[0004]

The pattern center is sandwiched between the V and V at a relatively large inclination angle with respect to the circumferential direction.
In a pneumatic tire having a tread pattern in which a large number of directional high-inclination grooves extending in a letter shape are arranged at intervals in the tire circumferential direction, there is a strong tendency for frequent heel and toe wear. Heel and toe wear is a type of uneven wear of tires and treads. The block surface, which was flat (correctly speaking, a curved surface with a large radius of curvature) when it was new, tilted in the circumferential direction after running the tire. Wears
The wear is saw-toothed when viewed in a circumferential section. In addition, a tread pattern in which a large number of directional high-inclination grooves extending in a V shape at a relatively large inclination angle with respect to the circumferential direction sandwiching the pattern center is arranged at intervals in the tire circumferential direction. Pneumatic tire provided with, compared to a pneumatic tire with a circumferential groove extending parallel to the circumferential direction,
The noise generated from the tires when driving is large. Pitch variation has been known as a technique for reducing tire noise, and has been put to practical use. this is,
A method for reducing tire noise based on the theory of frequency modulation, in which the circumferential length (pitch) of the minimum unit pattern constituting the pattern is set to two or more types, and is appropriately set on the circumference of the tire / tread. By arranging the tires, the tire noise is reduced by dispersing the noise generated from the tires into many sidebands having a low sound pressure level. Strictly speaking, however, this pitch variation method is a method of widely dispersing the frequency of tire noise to make it difficult to hear the tire noise, and does not reduce the noise energy itself.

An object of the present invention is to eliminate the above-mentioned problems of the prior art and to sandwich the pattern center on the left and right sides.
A heel which frequently occurs in a pneumatic tire having a tread pattern in which a plurality of directional high-inclination grooves extending in a V shape at a relatively large inclination angle with respect to the circumferential direction are arranged at intervals in the tire circumferential direction. And toe wear is prevented or suppressed, and at the same time, the energy of noise generated from the tire itself is reduced to reduce the tire noise in the original sense.

[0006]

In order to achieve the above object, the pneumatic tire of the present invention has a pattern center between which the angle is 45 to 90 degrees, preferably 60 to 80 degrees in the circumferential direction. In a pneumatic tire having a tread pattern in which a large number of directional high-inclination grooves extending in a V shape are arranged at a relatively large inclination angle and are arranged at intervals in the tire circumferential direction, at least from the pattern center to the tread. In the tread outer region from the position of about 50% of the distance to both ends to both ends of the tread, preferably in the entire tread region, with respect to the tread normal line in the cross section of the directional high-inclination groove in the direction perpendicular to the groove extending direction. Among the angle of the groove side wall, the angle of the groove side wall that comes into contact with the ground later when the tire rotates normally is larger than the angle of the groove side wall that comes into contact with the ground first. That is a pneumatic tire.

In the pneumatic tire of the present invention, in the tread outer region from the position of about 50% of the distance from the pattern center to both ends of the tread to the both ends of the tread,
Among the angles of the groove sidewalls with respect to the tread normal in the cross section in the direction perpendicular to the direction in which the groove extends, the angle of the groove sidewall that comes into contact later when the tire rotates in the forward direction is the angle of the groove sidewall that comes into contact with the tire first. In the tread inner area inside the position where the angle is larger and is about 50% of the distance from the pattern center to both ends of the tread, the tread method in the cross section of the directional high-inclination groove in the direction perpendicular to the groove extending direction. Among the angles of the groove side walls with respect to the line, the angle of the groove side wall that comes into contact later when the tire rotates in the forward direction is smaller than the angle of the groove side wall that comes into contact with the tire first, and in the connection area between the tread outer area and the tread inner area. The angle of the groove side wall with respect to the tread normal line in the cross section perpendicular to the direction in which the groove extends, and the angle of the groove side wall to be grounded later when the tire rotates in the normal direction. It is preferred angle of the groove sidewall grounding are the same angle.

The pneumatic tire according to the present invention has a relatively small inclination angle of 5 to 30 degrees, preferably 10 to 20 degrees with respect to the circumferential direction on both sides of the pattern center, and V
It is preferable that a large number of directional low-inclination grooves extending in a letter shape are arranged at intervals in the tire circumferential direction.

[0009]

In the pneumatic tire of the present invention, the inclination angle of the directional high inclination groove is preferably 45 to 90 degrees.
More preferably, it is 0 to 80 degrees. If this angle is too small, the angle of intersection between the directional low-tilt groove and the directional high-tilt groove will be small, resulting in insufficient block rigidity and poor steering stability on dry road surfaces, as well as uneven wear. Become. In addition, the block formed between the directional low-inclination groove and the directional high-inclination groove becomes small, the block rigidity becomes insufficient, and the steering stability on a dry road surface deteriorates. If this angle is too large, the tread's grounded stepping end will coincide with the stepping corner of the directional high-inclination groove, and noise will increase.

In the pneumatic tire of the present invention, in addition to the directional high-inclination groove, it is preferable to provide a directional low-inclination groove having an inclination angle of 5 to 30 degrees, and the inclination angle is 10 to 20 degrees. Is more preferable. If this angle is too small, the block formed between the directional low-inclination grooves becomes small, the block rigidity becomes insufficient, and the steering stability on a dry road surface deteriorates. Therefore, in order to increase the size of the block in order to increase the block rigidity, the pitch must be set to a large value, and the number of pitches must be reduced. It stands out. If this angle is too large, the drainage performance on the wet road surface due to the directional low inclination groove is deteriorated, and the function of preventing or suppressing the hydroplaning phenomenon is reduced. Further, the angle of intersection between the low-directional directional groove and the high-directional directional groove becomes small, the block rigidity becomes insufficient, the steering stability on the dry road surface deteriorates, and uneven wear easily occurs.

As described above, a large number of directional high-inclination grooves extending in a V shape at a relatively large inclination angle with respect to the circumferential direction sandwiching the pattern center are arranged at intervals in the tire circumferential direction. Conventional pneumatic tires with a tread pattern tend to have high heel and toe wear, especially from about 50% of the distance from the pattern center to both ends of the tread to both ends of the tread. This tendency is strong in the outer region of the tread, which is the region of. Further, as described above, the pneumatic tire of the present invention preferably has a directional low-tilt groove in addition to the directional high-tilt groove. In that case, the directional low-tilt groove having a grazing angle relationship with the circumferential direction is provided. Since the groove is inclined from the pattern center to the tread outer region to divide the entering directional high-inclination groove, the rigidity of the block in the tread outer region formed by the directional high-inclination groove and the directional low-inclination groove is Non-uniformity is likely to occur on the circumference, and the above heel and toe wear is more likely to occur. In the pneumatic tire of the present invention, at least in the tread outer region, among the groove side wall angles with respect to the tread normal in the cross section in the direction perpendicular to the direction in which the groove of the directional high-inclination groove extends, the groove side wall to be grounded later during normal rotation of the tire. The angle is larger than the groove side wall angle that comes in contact with the ground first, in other words, when focusing on the block formed by the directional high inclination groove, the groove side wall angle located on the stepping side of the block is the kicking side of the same block. This is larger than the side wall angle of the groove located at, and therefore the rigidity on the stepping side of the block is strong and the rigidity on the kicking side is weak, so there is no "escape" to the kicking side of the block when the tire rolls. The behavior is enabled to prevent or suppress heel and toe wear. If attention is paid only to the prevention or suppression of heel-and-toe wear, the pneumatic tire of the present invention is not limited to the tread outer region, and the entire tread region has the same groove sidewall angle on the stepping side of the block. The angle is preferably larger than the side wall angle of the groove located on the kicking side.

A tread pattern in which a large number of directional high-inclination grooves extending in a V shape at a relatively large inclination angle with respect to the circumferential direction sandwiching the pattern center are arranged at intervals in the tire circumferential direction. In a pneumatic tire provided with, not only the prevention of heel and toe wear but also the suppression thereof, it is sometimes required to reduce the noise generated while the tire is running. Noise generated while the tire is running
"Groove air pumping sound", "Block or lug vibration sound" and "Other sounds (ground friction sound, noise caused by tire vibration due to uneven road surface, or air pumping sound in recessed road surface, etc.)" However, it is the former two that the patterns such as lugs, ribs or blocks formed on the tread surface of the tire by the grooves are the generation sources. Further, in a tire provided with a block pattern or a lug pattern, the "block or lug vibration sound" tends to be loud. For pneumatic tires with a block or lug pattern, when the tire rolls, the block or lug collides with the road surface when the discontinuity on the tread rubber surface that is the boundary between the block and the lug and lug touches the ground. Then, the impact force causes the block or lug to vibrate and emit a sound (block or lug excitation sound). Sound emission acts as a speaker, so to speak, with the side walls of the tire and the tread surface acting as a diaphragm.

In a pneumatic tire provided with a highly inclined groove extending in a direction inclined at a relatively large angle with respect to the circumferential direction,
Of the side walls of the high-sloping groove, the side wall that comes into contact with the ground later during rolling of the tire collides with the road surface when the vehicle is just stepping on the ground, and the impact force causes the block or lug to vibrate and emit the loudest sound. In other words, paying attention to the block formed by the directional high-inclination groove, in other words, the corner on the stepping side of the block (the corner that comes in contact with the ground first when the tire rolls) collides with the road surface just when stepping on the ground, Generates noise. The tire noise is generated more in the tread inner area than in the tread outer area. As described above, the pneumatic tire of the present invention has a directional high-inclination groove at a right angle to the direction in which the groove extends in the tread inner area inside about 50% of the distance from the pattern center to both ends of the tread. Among the angles of the groove side walls with respect to the tread normal in the direction cross section, the angle of the groove side wall that comes into contact later when the tire rotates normally is smaller than the angle of the groove side wall that comes in contact with the tire first, so The rigidity is weakened, the impact force when colliding with the road surface is alleviated,
The tire noise will be suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is a partially enlarged front view of a tread pattern of a pneumatic tire for passenger cars according to the embodiment of the present invention. 225 / 50R16. The tire tread of Example 1 according to the present invention shown in FIG.
The pattern has a large number of directional high-inclination grooves (2) that extend in a V-shape at a relatively large inclination angle of about 65 degrees with respect to the circumferential direction across the equatorial line (E) of the tire that is the pattern center. Are arranged at intervals in the tire circumferential direction.
In addition to the directional high-inclination groove (2), a large number of V-shapes are extended to the left and right across the equatorial line (E) of the tire which is the pattern center at a relatively small inclination angle of about 18 degrees with respect to the circumferential direction. The directional low-inclination grooves (1) are arranged at intervals in the tire circumferential direction, and the V-shaped center block is formed by the directional low-inclination grooves (1). In the tire of Example 1 according to the present invention shown in FIG. 1, the side close to the tire equatorial plane of the directional low inclination groove (1) and the high directional high inclination groove (2) comes into contact first, and the side far from the tire equatorial plane is It is provided with a so-called directional tread pattern in which the direction of rotation (R) of the tire when it is mounted on the vehicle is specified so that it will be grounded later. As shown in the AA cross-sectional view, in the tread outer region (S) from the position of 50% of the distance from the pattern center to both ends of the tread to the both ends of the tread, the groove of the directional high inclination groove (2) extends. Among the angles of the groove side wall with respect to the tread normal (N) in the cross section perpendicular to the direction, the angle (α) of the groove side wall on the side to be grounded later when the tire rotates normally is 2
At 5 degrees, the angle (β) of the groove side wall on the side that comes into contact with the ground first when the tire rotates normally is 0 degree. 50% of the distance from the pattern center to both ends of the tread as shown in the BB cross section
In the inner region (C) of the tread inside from the position of, the positive angle of the tire is included in the angle of the groove sidewall with respect to the tread normal (N) in the cross section of the directional high-inclination groove (2) in the direction perpendicular to the groove extending direction. Angle (γ) of the side wall of the groove that will contact the ground later when rolling
Is 10 degrees, and the angle (δ) of the side wall of the groove to be grounded first is 15 degrees. In the connection region between the tread outer region (S) and the tread inner region (C), the angle of the groove sidewall with respect to the tread normal line in the cross section of the directional high-inclination groove (2) in the direction perpendicular to the groove extending direction, The angle of the side wall of the groove which comes into contact later with the normal rotation of the tire and the angle of the side wall of the groove which comes into contact with the front are the same angle of 15 degrees. The groove width (W) of the directional highly inclined groove (2) is 5.5 mm and the groove depth (D) is 6 mm. The angle of the side wall of the directional low inclination groove (1) is 20 degrees on both the stepping side and the kicking side, the groove width (W) is 11 mm, and the groove depth (D) is 8 mm.

In the tire of Example 2 according to the present invention, in the tread outer area (S), the angle (α) of the groove side wall on the side to be grounded later when the tire rotates normally is 20 degrees, and when the tire rotates normally, The angle (β) of the side wall of the groove on the side that contacts the ground is 5 degrees,
In the inner area of the tread (C), the directional highly inclined groove (2)
Of the side wall of the groove that comes into contact with the ground during normal rotation of the tire (γ)
Is 10 degrees and the angle (δ) of the side wall of the groove to be grounded first is also the same as that of the tire of Example 1.

In the pneumatic tire of the conventional example, the left and right groove sidewall angles with respect to the tread normal (N) are the same at any position of the directional high-inclination groove (2) in a cross section perpendicular to the direction in which the groove extends. Example 1 except that the angle is 15 degrees
It is the same as the pneumatic tire of.

Regarding the pneumatic tires of Examples 1 and 2 according to the present invention and the pneumatic tires of the above-mentioned conventional examples,
A comparative test of heel and toe wear and tire noise was conducted. A comparison test of heel and toe wear is
Test tires were attached to the idle wheels of a domestic 2000cc class passenger car, and the maximum value of heel and toe wear after running 10,000 km was measured. In the tire noise comparison test, an indoor evaluation test of tire noise was performed based on the automobile standard tire noise test method JASO C606. The test conditions are as follows: used rim 8J × 16, tire internal pressure 3.1 kgf / c
At m ² , the load is 500 kgf and the speed is 60 km / h.
The measurement item is noise (sound pressure level) in all frequency bands.
Table 1 shows the test results.

[0018]

[Table 1]

[0019]

From the results shown in Table 1, the pneumatic tires of Examples 1 and 2 according to the present invention suppress the occurrence of heel-and-toe wear as compared with the pneumatic tires of the conventional example, and the tire noise. It can be seen that is significantly reduced.

[Brief description of the drawings]

1 is a partially enlarged front view and groove sectional view of a tread pattern of a pneumatic tire according to the present invention.

[Explanation of symbols]

 1 Directional low inclination groove 2 Directional high inclination groove C Tread inner area D Directional high inclination groove depth E Tire equatorial line N Tread normal R Tire rotation direction S Tread outer area W Directional high inclination groove Groove width α Sidewall angle of directional high-slope groove β Sidewall angle of directional high-slope groove γ Sidewall angle of directional high-slope groove δ Sidewall angle of directional high-slope groove

Claims (6)

[Claims] 1. A relatively large inclination angle of 45 to 90 degrees with respect to the circumferential direction on the left and right sides of the pattern center,
In a pneumatic tire having a tread pattern in which a large number of V-shaped directional high-sloping grooves are arranged at intervals in the tire circumferential direction, at least about 50 times the distance from the pattern center to both ends of the tread. In the tread outer area from the position of about% to both ends of the tread,
Among the angles of the groove sidewalls with respect to the tread normal in the cross section in the direction perpendicular to the direction in which the groove extends, the angle of the groove sidewall that comes into contact later when the tire rotates in the forward direction is the angle of the groove sidewall that comes into contact with the tire first. A pneumatic tire characterized by a larger angle. 2. In the entire tread area, among the angles of the groove side walls with respect to the tread normal in a cross section of the directional high-inclination groove in a direction perpendicular to the direction in which the groove extends, the angle of the groove side wall to be grounded later when the tire rotates normally. The pneumatic tire according to claim 1, wherein the angle is larger than the angle of the side wall of the groove that comes into contact with the ground first. 3. A tread normal line in a cross section of the directional high-inclination groove in a cross section perpendicular to a direction in which the groove extends, in a tread inner area inside about 50% of a distance from the pattern center to both ends of the tread. Among the angles of the groove side wall with respect to, the angle of the groove side wall that comes into contact later when the tire rotates normally is smaller than the angle of the groove side wall that comes into contact with the tire first,
In the connection region between the tread outer region and the tread inner region, the angle of the groove sidewall with respect to the tread normal line in the cross section of the directional high-inclination groove in the direction perpendicular to the direction in which the groove extends,
2. The pneumatic tire according to claim 1, wherein the angle of the side wall of the groove which comes into contact with the ground later when the tire is rotated normally and the angle of the side wall of the groove which comes into contact with the ground first are the same. 4. The tilt angle of the directional high tilt groove with respect to the circumferential direction is 60 to 80 degrees.
The pneumatic tires according to 1 to 3. 5. A relatively small inclination angle of 5 to 30 degrees with respect to the circumferential direction on the left and right sides of the pattern center, and V
The pneumatic tire according to claim 1, wherein a large number of directional low-inclination grooves extending in a letter shape are arranged at intervals in the tire circumferential direction. 6. The tilt angle of the directional low tilt groove with respect to the circumferential direction is 10 to 20 degrees.
The pneumatic tire as described.