WO2016001995A1

WO2016001995A1 - Pneumatic tire

Info

Publication number: WO2016001995A1
Application number: PCT/JP2014/067459
Authority: WO
Inventors: 手塚　隆
Original assignee: コンパニーゼネラールデエタブリッスマンミシュラン; ミシュランルシェルシュエテクニークソシエテアノニム; 手塚　隆
Priority date: 2014-06-30
Filing date: 2014-06-30
Publication date: 2016-01-07

Abstract

Provided is a pneumatic tire with higher-level noise abatement. This pneumatic tire (1) comprises: a tread portion (2) comprising at least one circumferential groove (5), multiple transverse grooves (6), and, separated by the circumferential grooves (5) and the transverse grooves (6), multiple ground contact elements (7) having a circumferential length BL and an axial width BW; an undertread portion provided adjacently to the radially inner side of the tread portion (2); and at least one ply provided adjacently to the radially inner side of the undertread portion and extending in the tire circumferential direction. The undertread portion comprises: softening elements (8) which are provided so as to cover part of or the entire range in the circumferential direction of a ground contacting element (7) formed on the tread portion (2), and, in the tire axial direction, to cover at least 30% of the range of the ground contacting element (7) in the axial width direction BW; and non-softened portions (9) which are disposed between softening elements (8) adjacent in the circumferential direction and which are disposed to the radially inner side of a transverse groove formed on the tread portion (2).

Description

Pneumatic tire

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of improving noise performance.

In recent years, from the viewpoint of occupant comfort associated with higher-grade and higher-quality vehicles and consideration for the environment, it is desired to reduce various types of noise, particularly passing noise. Such a noise is generated when a running tire vibrates due to the unevenness of the road surface and the vibration is transmitted to vibrate the structural member of the tire. Therefore, in order to reduce the vibration generated with the rotation of the tire, a method of forming the tread portion and / or the under tread portion with a rubber composition having a low hardness, or a predetermined amount with respect to the tire axial direction on the tire tread portion. There is known a pneumatic tire that employs a method of forming a so-called lateral groove so as to extend at an angle.

However, in a pneumatic tire in which the tread portion and / or the under tread portion is made of a rubber composition having a low hardness, since the tread portion and / or the under tread portion is soft throughout, the steering stability is reduced. End up. Further, in a pneumatic tire in which a lateral groove is formed in the tire tread portion so as to extend at a predetermined angle with respect to the tire axial direction, steering stability is reduced due to a decrease in lateral rigidity of the block facing the lateral groove. It is known. Therefore, Patent Document 1 (mainly FIG. 1) describes a pneumatic tire in which a contact pressure absorbing layer is provided on the radially outer peripheral side of the belt layer so as to extend in the tire circumferential direction.

Further, Patent Document 2 (mainly FIG. 1) describes a pneumatic tire in which a contact pressure absorbing member extending in the tire circumferential direction is provided in the vicinity of the groove bottom of the tire circumferential groove.

JP 2007-045358 A JP 2002-059708 A

However, in the pneumatic tires described in Patent Documents 1 and 2, the ground pressure absorbing layer (or ground pressure absorbing member) is disposed substantially uniformly over the entire circumference of the tire. On the other hand, because the tread pattern has a non-uniformity in the flexural rigidity of the tread, vibration reduction by the ground pressure absorbing layer (or ground pressure absorbing member) is insufficient, and tire rotation There is a problem that the effect of reducing the noise generated based on the vibration generated is not sufficient.

Therefore, the present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a pneumatic tire in which noise is reduced at a higher level.

Definition:
In this specification, the “groove” is configured by connecting two opposing surfaces (wall surface, side wall) that do not contact each other under normal use conditions by another surface (bottom surface). A space with a width and depth.

The “ply” is a single wire or a twist of a metal wire or a fiber wire such as iron, polyester, nylon, etc., which is coated with a rubber composition and extends in parallel with the rubber composition, extending radially inward of the tread portion of the tire. A layer consisting of lines. The extending direction of the metal wire or the fiber wire constituting the ply may be different from the tire rotation direction.

In order to achieve the above object, the present invention provides at least one circumferential groove that continuously opens in the tire circumferential direction and that opens in the ground contact surface that is in contact with the road surface during tire rolling, and that opens in the ground contact surface. A plurality of lateral grooves extending in the axial direction, a tread portion having a plurality of grounding elements defined by the circumferential grooves and the lateral grooves and having a circumferential length BL and an axial width BW, and a radial direction of the tread portion An under tread portion, comprising: an under tread portion provided adjacent to an inner side; and at least one ply provided adjacent to a radially inner side of the under tread portion and extending in a tire circumferential direction. Covers a partial range or the entire range of the grounding element formed in the tread portion in the tire circumferential direction, and covers at least 30% of the axial width BW of the grounding element in the tire axial direction. It is characterized by having a softening element provided and a non-softening part provided between the softening elements radially inward of the lateral groove formed in the tread portion and adjacent in the circumferential direction. .

In the present invention configured as described above, the under tread portion covers a partial range or the entire range of the grounding element formed in the tread portion in the tire circumferential direction, and at least the grounding element in the tire axial direction. By having a softening element provided so as to cover a range of 30% of the axial width BW, it is possible to alleviate unevenness in the bending rigidity of the tread due to the presence of the lateral groove in the tread pattern. I can do it. Thereby, the vibration generated with the rotation of the tire can be reduced, and as a result, noise can be reduced.

Further, in the present invention, the under tread portion has a non-softening portion provided between the softening elements adjacent to each other in the radial direction inside the lateral groove formed in the tread portion and in the circumferential direction. Further, it is possible to prevent the bending rigidity of the grounding element portion of the tread portion from being too low with respect to the lateral groove portion due to the provision of the softening element in the under tread portion. Thereby, the non-uniformity of the bending rigidity of the tread portion can be further reduced, and the vibration generated with the rotation of the tire can be further reduced, and as a result, the noise can be further reduced.

In the present invention, preferably, the circumferential length of the non-softening portion is not less than 100% and not more than 150% of the circumferential groove width of the lateral groove.
In the present invention configured as described above, it is possible to prevent the bending rigidity of the tread portion of the lateral groove portion from becoming too low by appropriately maintaining the circumferential length of the non-softening portion, and it is more effective. Noise can be reduced.
In other words, if the circumferential length of the non-softening part is less than 100% of the circumferential groove width of the transverse groove, the flexible element extends circumferentially to the extent of the transverse groove when manufacturing the tire. There is a possibility that the tire will increase and tire productivity may be reduced. In addition, when the circumferential length of the non-softening portion is larger than 150% of the circumferential groove width of the lateral groove, the circumferential length of the adjacent softening portion is not sufficient, and the bending rigidity of the tread portion is not sufficient. The non-uniformity of the noise becomes insufficient, and there is a risk that noise cannot be reduced sufficiently.

In the present invention, preferably, the axial width of the softening element is 60% or more and 95% or less of the axial width BW of the grounding element.
In this invention comprised in this way, the softening effect of the range of the area | region inside the radial direction of the grounding element by a softening element can be exhibited efficiently, and noise can be reduced more effectively.
In other words, if the axial width of the softening element is smaller than 60% of the axial width BW of the grounding element, the softening effect of the inner area in the radial direction of the grounding element by the softening element is not sufficient, and the tread portion There is a possibility that the unevenness of the bending rigidity of the material becomes insufficient and noise cannot be sufficiently reduced. Also, if the axial width of the softening element is greater than 95% of the axial width BW of the grounding element, the softening element may reach the radially inner range of the circumferential groove during tire manufacture. This may increase the tire productivity.

In the present invention, preferably, the tire radial thickness t of the softening element is 60% or more and 95% or less of the radial thickness of the undertread portion.
In the present invention configured as described above, the softening effect in the range of the grounding element of the tread portion by the softening element arranged in the under tread portion can be efficiently exhibited, and the noise is more effectively reduced. be able to.
In other words, if the tire radial thickness t of the softening element is less than 60% of the radial thickness of the undertread part, the softening effect of the softening element in the radial inner range of the grounding element of the tread part Is not sufficient, and the unevenness of the bending rigidity of the tread portion is insufficiently mitigated, so that the noise may not be sufficiently reduced. In addition, when the tire radial thickness t of the softening element is larger than 95% of the radial thickness of the under tread portion, the softening effect of the softening element in the radial inner side range of the grounding element of the tread portion is obtained. Since it becomes excessive and relaxation of the non-uniformity of the bending rigidity of the tread portion becomes insufficient, there is a possibility that noise cannot be reduced sufficiently.

In the present invention, preferably, the radial distance between the radially innermost side of the softening element and the radially outermost side of the ply is 0.1 mm or more and 1.0 mm or less.
In the present invention configured as described above, the softening effect in the range corresponding to the grounding element by the softening element arranged in the under tread portion can be efficiently exhibited, and noise can be reduced more effectively. I can do it.
In other words, if the tire radial distance between the innermost radial direction of the softening element and the outermost radial direction of the ply is smaller than 0.1 mm, the softening element will be too close to the ply, so the durability of the undertread part May decrease. Also, if the tire radial distance between the innermost radial direction of the softening element and the outermost radial direction of the ply is larger than 1.0 mm, the flexural rigidity placed in the under tread part will move away from the ply. Since the reduction effect becomes small and the relaxation of the non-uniformity of the bending rigidity of the tread portion becomes insufficient, there is a possibility that noise cannot be reduced sufficiently.

The pneumatic tire according to the present invention can reduce noise more effectively.

It is a figure showing typically some pneumatic tires by an embodiment of the present invention. It is an expanded sectional view of the pneumatic tire seen along the II-II line of FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
First, a pneumatic tire according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a view schematically showing a part of a pneumatic tire according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view of the pneumatic tire taken along line II-II in FIG. .

As shown in FIG. 1, reference numeral 1 denotes a pneumatic tire according to an embodiment of the present invention. The tire size of the pneumatic tire 1 is, for example, 205 / 55R16. In the tire 1, the internal structure other than the tread portion 2, the under tread portion 3, and the ply 4 described below is the same as that of a normal radial tire, and thus description thereof is omitted here.

Next, the overall configuration of the pneumatic tire 1 will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the tire 1 has a tread portion 2 on a radially outer peripheral portion. The tread portion 2 has a ground contact surface 21 that comes into contact with the road surface during rolling of the tire. The ground contact surface 21 of the tread portion 2 includes a circumferential groove 5 continuously extending in the tire circumferential direction and a plurality of tire grooves extending in the tire axial direction. A transverse groove 6 is formed. Furthermore, a plurality of ground elements 7 having a circumferential length BL and an axial width BW are defined in the tread portion 2 by a circumferential groove 5 and a lateral groove 6. In the present embodiment, the circumferential width of the lateral groove 6 is 5 mm, the circumferential length BL of the grounding element 7 is 25 mm, and the axial width BW is 40 mm.

Next, as shown in FIG. 2, the pneumatic tire 1 is adjacent to the tread portion 2 so as to be adjacent to the inner side in the radial direction, and to be adjacent to the under tread portion 3 in the radial direction. And a ply 4 disposed on the surface. The under tread portion 3 is provided with a softening element 8, and a non-softening portion 9 is formed between the softening elements 8 adjacent to each other in the tire circumferential direction.

Next, the arrangement and configuration of the softening element 8 and the non-softening part 9 of the undertread part 3 will be described.
As shown in FIGS. 1 and 2, in this embodiment, the softening element 8 has a tire radial thickness t and is located within a region in which the ground contact element 7 of the undertread portion 3 is projected in the radial direction. ing. That is, in the present embodiment, each of the softening elements 8 is located between the circumferential edges of the corresponding grounding elements 7 when the circumferential edges are viewed from the outer side in the tire radial direction, and The edges at both ends in the axial direction are located between the edges at both ends in the axial direction of the corresponding grounding element 7.

In this embodiment, the axial width of the softening element 8 is 75% of the axial width BW of the grounding element 7 (see FIG. 1), and the softening element 8 is 75% of the axial width BW of the grounding element 7. Covers% range. The tire radial thickness t of the softening element 8 is 90% of the radial thickness of the undertread portion 3, and is between the radial innermost side of the softening element 8 and the radial outermost side of the ply 4. The radial distance is 0.5 mm.

In the present embodiment, the softening element 8 is provided so as to cover a partial range of the grounding element 7 in the circumferential direction, but is not limited thereto, and covers the entire range of the grounding element 7 in the circumferential direction. It may be provided as follows. However, it is preferable that the softening element 8 does not extend to the radially inner region of the lateral groove 6. Further, the axial width of the softening element 8 is not limited to 75% of the axial width BW of the grounding element 7, but is preferably 60% or more and 95% or less of the axial width BW of the grounding element 7. . Further, in this embodiment, the softening element 8 covers a range of 75% of the axial width BW of the grounding element 7, but is not limited to this, and at least 30 of the axial width BW of the grounding element 7 in the axial direction. It is preferable to be provided so as to cover the% range. Further, the tire radial thickness t of the softening element 8 is not limited to 90% of the radial thickness of the undertread portion 3, but is 60% or more and 95% or less of the radial thickness of the undertread portion 3. It is preferable that The radial distance between the radially innermost side of the softening element 8 and the radially outermost side of the ply 4 is not limited to 0.5 mm, but is preferably 0.1 mm or more and 1.0 mm or less.

Each non-softening part 9 is located between the softening elements 8 adjacent in the circumferential direction, and has the same axial width as the softening elements. In addition, the circumferential length of the non-softening portion 9 is 125% of the circumferential groove width of the lateral groove 6, and the non-softening portion 9 extends in the range of the lateral groove 6 and the lateral groove 6 in the circumferential direction. It extends over the area of the edge of the adjacent grounding element 7 on both sides. The circumferential length of the non-softening portion 9 is preferably 100% or more and 150% or less of the circumferential groove width of the lateral groove 6.

The material constituting the softening element 8 is not particularly limited, and for example, a rubber composition in which the reinforcing filler is extremely reduced or not contained, a gel-like composition, and the like can be used. Moreover, as a material which comprises the softening element 8, you may use the rubber composition whose JIS A hardness is 10 degrees or more lower than the rubber composition which comprises the undertread part 3, for example. In this embodiment, the softening element 8 does not contain a reinforcing filler, and is a rubber composition having a lower rigidity than the rubber constituting the other part of the tire.

Moreover, the non-softening part 9 can be comprised with the same material as the rubber composition etc. which comprise the under-tread part 3 or the tread part 2. FIG. Moreover, the non-softening part 9 does not have a softening effect (that is, the rigidity is higher than that of the rubber composition constituting the undertread part 3 or the tread part 2), and constitutes the undertread part 3 or the tread part 2. It can also be comprised with other materials different from a rubber composition etc., for example, polyethylene terephthalate etc. In the present embodiment, the non-softening portion 9 is the same rubber composition as the undertread portion 3.

Next, main effects of the present embodiment will be described.
When the tire rolls and the ground contact surface 21 (ground contact element 7) of the tread portion 2 comes into contact with the road surface or is deformed away from the road surface, the tread portion 2 is provided with the lateral grooves 6, so that the under tread portion 3 and the tread portion 2, in particular, the bending rigidity of the tread portion 2 is non-uniform. Then, the ply 4 is vibrated due to the non-uniform rigidity, and vibration accompanying rotation of the tire is generated, and this vibration becomes noise. On the other hand, according to the present embodiment, the under tread portion 3 covers a partial range or the entire range of the grounding element 7 in the circumferential direction, and at least the axial width BW of the grounding element 7 in the axial direction. Since the softening element 8 having a tire radial thickness t is provided so as to cover the range of 30%, the uneven rigidity of the bending rigidity of the undertread part 3 and the tread part 2, particularly the tread part 2 is alleviated. As a result, noise can be reduced.

The effect of alleviating the non-uniformity in bending rigidity of the undertread part 3 and the tread part 2, particularly the tread part 2, is the radial inner side of the lateral groove 6 formed in the tread part 2 of the undertread part 3, and The non-softening portion 9 provided between the softening elements 8 adjacent in the circumferential direction can be further improved, and as a result, noise can be further reduced.

Next, a modification of this embodiment will be described.
The softening element 8 arranged in the under tread portion 3 covers a partial range or the entire range of the grounding element 7 in the circumferential direction, and at least 30% of the axial width BW of the grounding element 7 in the axial direction. A plurality of softening elements having a small axial width may be juxtaposed in the tire axial direction as long as they are provided so as to cover the tire. In this case, the width in the tire axial direction of the softening element 8 is such that the sum of the tire axial widths of the plurality of softening elements provided for each grounding element 7 is 60% of the axial width BW of the grounding element 7. It is preferable that the amount is 95% or less.

Further, a plurality of thin softening elements 8 laminated in the tire radial direction may be provided in the under tread portion 3. In this case, the tire radial thickness t of the softening element 8 is the sum of the tire radial thicknesses of a plurality of softening elements provided for a certain grounding element 7. It is preferable to be 60% or more and 95% or less.

The non-softening portion 9 is preferably provided symmetrically in the circumferential direction with respect to the circumferential center of the lateral groove 6 as in the present embodiment, but the lateral groove in the circumferential direction of the undertread portion 3. It extends beyond 6 and may be arranged asymmetrically in the tire circumferential direction with respect to the circumferential center of the lateral groove 6.

In the present embodiment, the softening element 8 is provided in the radially inner region of all the grounding elements 7 in the undertread portion 3, but the grounding elements 7 positioned on the outer side in the tire axial direction are provided. You may arrange | position so that the softening element 8 may be provided only in the area | region inside radial direction.

As mentioned above, although especially preferable embodiment of this invention was described, this invention can be deform | transformed and implemented in various aspects, without being limited to embodiment of illustration.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 21 Grounding surface 3 Under tread part 4 Ply 5 Circumferential groove 6 Lateral groove 7 Grounding element (block)
8 Flexible elements 9 Non-flexible parts

Claims

At least one circumferential groove (5) that opens to the ground contact surface (21) that contacts the road surface during tire rolling and extends continuously in the tire circumferential direction, and a plurality of holes that open to the ground contact surface and extend in the tire axial direction. A tread having a transverse groove (6) and a plurality of grounding elements (7) defined by the circumferential groove (5) and the transverse groove (6) and having a circumferential length BL and an axial width BW Part (2),
An under tread portion (3) provided adjacent to the inner side in the radial direction of the tread portion (2);
A pneumatic tire (1) having at least one ply (4) provided adjacent to a radially inner side of the undertread portion (3) and extending in a tire circumferential direction,
The under tread portion (3) covers a partial range or the entire range of the ground contact element (7) formed in the tread portion (2) in the tire circumferential direction, and at least the ground contact element in the tire axial direction. The softening element (8) provided so as to cover a range of 30% of the axial width BW of (7), and the radially inner side of the lateral groove (6) formed in the tread portion (2) And a non-softening portion (9) provided between the softening elements (8) adjacent in the circumferential direction.
The pneumatic tire according to claim 1, wherein a circumferential length of the non-softening portion (9) is not less than 100% and not more than 150% of a circumferential groove width of the lateral groove (6).
The pneumatic tire according to claim 1 or 2, wherein an axial width of the softening element (8) is 60% or more and 95% or less of the axial width BW of the ground contact element (7).
The tire radial direction thickness t of the softening element (8) is 60% or more and 95% or less of the radial thickness of the undertread part (3). The described pneumatic tire.
The tire radial direction distance between the radially innermost side of the softening element (8) and the radially outermost side of the ply (4) is not less than 0.1 mm and not more than 1.0 mm. The pneumatic tire according to claim 1.