JP6781541B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

Conventionally, as a pneumatic tire, a tire in which the groove angle of the lateral groove of the tread portion is changed with respect to the block rows arranged in the tire circumferential direction is known (see, for example, Patent Documents 1 and 2).

However, with the conventional pneumatic tire, pumping noise cannot be sufficiently reduced. For example, in the pneumatic tire described in Patent Document 1, the noise level can only be set to almost the same level as the conventional one.

Japanese Patent No. 3108888 Japanese Unexamined Patent Publication No. 2013-237362

An object of the present invention is to provide a pneumatic tire having a function of reducing pumping noise and a method for manufacturing the same.

The present invention provides means for solving the above problems.
A pneumatic tire having a plurality of blocks formed in a tread portion by a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction.
The block has a cross section orthogonal to the extension direction of the lateral groove formed in the same cross-sectional shape over the lateral groove, and in the cross section, the central portion in the depth direction faces the both side surfaces constituting the lateral groove. A convex portion having a triangular cross section that protrudes most toward the tire is formed, whereby the distance between both side surfaces is increased or decreased in the tire radial direction .
The cross-sectional shape of the lateral groove, which is orthogonal to the extension direction of the lateral groove, gradually narrows from the upper surface side edge toward the tire inner diameter direction, becomes the narrowest at the central portion in the depth direction, and then gradually narrows toward the groove bottom. Provided is a pneumatic tire that is wider and has the same width as the upper surface side edge at the groove bottom .

With this configuration, even if the surface (tread surface) of the tread portion comes into contact with the road surface and the block is compressed, both side surfaces constituting the lateral groove are less likely to be deformed, and the volume change of the lateral groove can be suppressed. Therefore, it is possible to reduce pumping noise.

The lateral grooves between the blocks arranged side by side in the tire circumferential direction in the tread portion are preferably made of a plurality of types having different cross-sectional shapes in the cross section orthogonal to the extension direction of the lateral grooves.

With this configuration, the blocks sequentially come into contact with the road surface, the air in the lateral groove is compressed, and then the compressed air is released, but the frequencies of the pumping noise generated at this time can be different. Therefore, pumping noise of the same frequency does not repeatedly occur at regular intervals.

Among the lateral grooves, the lateral grooves juxtaposed in the tire width direction are preferably composed of a plurality of types having different cross-sectional shapes in the cross section orthogonal to the extension direction of the lateral grooves.

With this configuration, the block contacts the road surface to compress the air in the lateral groove, and then the block separates from the road surface to release the compressed air, but the pumping noise generated at that time is in the tire width direction. It differs between multiple lateral grooves located in. That is, the pumping noise does not increase at a constant frequency, and can be dispersed and suppressed.

The lateral groove preferably has two inclined surfaces whose side surfaces gradually approach each other from the tread surface and then gradually separate from each other.

With this configuration, it is possible to sufficiently suppress the volume change of the lateral groove when the block is deformed in contact with the road surface, and reduce pumping noise.

The lateral groove is preferably composed of a plurality of types in which the cross-sectional area of the cross section orthogonal to the tire width direction decreases at a constant rate.

With this configuration, the frequency at which pumping noise is generated can be effectively dispersed and suppressed.

According to the present invention, since the distance between both side surfaces forming the lateral groove is increased or decreased in the tire radial direction, the volume deformation of the lateral groove when the block contacts the road surface is reduced, and the generation of pumping noise is suppressed. be able to.

It is a partial development view of the tread part which concerns on this embodiment. It is sectional drawing in the cross section orthogonal to the tire width direction of the lateral groove of FIG. It is sectional drawing which made the cross-sectional area of the lateral groove 95% of FIG. 2 by forming the convex part on the side surface of the lateral groove of FIG. It is sectional drawing which made the cross-sectional area of the lateral groove 90% of FIG. 2 by forming the convex part on the side surface of the lateral groove of FIG. It is sectional drawing which made the cross-sectional area of the lateral groove 85% of FIG. 2 by forming the convex part on the side surface of the lateral groove of FIG. It is sectional drawing which made the cross-sectional area of the lateral groove 80% of FIG. 2 by forming the convex part on the side surface of the lateral groove of FIG. It is sectional drawing which made the cross-sectional area of the lateral groove 115% of FIG. 2 by forming the concave portion on the side surface of the lateral groove of FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. It should be noted that the following description is merely an example and is not intended to limit the present invention, its application, or its use. In addition, the drawings are schematic, and the ratio of each dimension is different from the actual one.

FIG. 1 is a partially developed view of a tread portion 1 of a pneumatic tire according to the present embodiment. Although not shown, this pneumatic tire has a configuration in which a carcass is hung between a pair of bead cores, reinforced by a belt wound around the outer peripheral side of the middle portion of the carcass, and a tread portion 1 is provided in the outer diameter direction of the tire. A plurality of blocks 4 are formed in the tread portion 1 by a plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 extending in the tire width direction.

The lateral groove 3 has five types of cross-sectional shapes shown in FIGS. 2 to 6. This is a cross-sectional shape of a cross section obtained by cutting in a plane orthogonal to the extension direction of the lateral groove 3 (here, the tire width direction), and is formed in the same cross-sectional shape over the entire lateral groove 3. ..

In FIG. 2, the cross section has a rectangular shape, and the facing side surfaces 7 extend parallel to the upper surface side edge 4a of the block 4 in the tire inner diameter direction. In FIGS. 3 to 6, convex portions 5 having a triangular cross section (the portion inside from the two-dot chain line in the drawing) are formed on both side surfaces 7 so that the central portion in the depth direction protrudes most in the opposite direction. .. As a result, inclined surfaces 6a and 6b are formed on the upper half and the lower half, respectively, and the distance between the side surfaces 7 increases or decreases from the upper surface side edge 4a of the tread surface toward the groove bottom 8. That is, the cross-sectional shape of the lateral groove 3 gradually narrows from the upper surface side edge 4a toward the inner diameter of the tire, narrows at the central portion in the depth direction, and then gradually widens toward the groove bottom 8. The groove bottom 8 has the same width as the upper surface side edge 4a. In FIG. 3, the protrusion amount of the convex portion 5 is set so that the occupied area of the lateral groove 3 in the cross section is 95% when the lateral groove 3 shown in FIG. 2 is 100%. Hereinafter, the protrusion amount of the convex portion 5 is set so as to be 90% in FIG. 4, 85% in FIG. 5, and 80% in FIG. That is, in each lateral groove 3, the cross-sectional area decreases at a constant rate (5%).

Since the lateral groove 3 has a cross-sectional shape having convex portions 5 on both side surfaces 7, even if the upper surface of the block 4 comes into contact with the road surface and deforms during traveling, the lateral grooves 3 are less likely to be deformed into the lateral groove 3 and the lateral groove The compression rate of the air in 3 can be reduced. That is, even if the air compression state in the lateral groove 3 is released by the rotation of the tire and the block 4 moving away from the road surface, the amount of air discharged from the lateral groove 3 is small, and the pumping noise generated can be suppressed. ..

In the lateral grooves 3 arranged in the tire circumferential direction, the cross-sectional shape is one of the above-mentioned five types. The lateral grooves 3 having different cross-sectional shapes are randomly arranged in the tire circumferential direction. Therefore, even if pumping noise is generated due to compression and release of air in the lateral groove 3 during traveling, the generation frequency can be made different between the lateral grooves 3 having different cross-sectional shapes. That is, an excessive peak value does not appear in the frequency of the generated pumping noise, and it can be suppressed by dispersing it.

Even in the lateral grooves 3 arranged in the tire width direction, those having different cross-sectional shapes are randomly arranged as in the circumferential block row. As a result, even if the block 4 touches the ground and is elastically deformed during traveling and the space in the lateral groove 3 is compressed and released to generate pumping noise, the generated frequency can be made different in each lateral groove 3. That is, an excessive peak value does not appear at the generation frequency of the pumping noise, and the pumping noise can be reduced as a whole.

In this way, the lateral grooves 3 having different cross-sectional shapes are randomly arranged in both the tire circumferential direction and the width direction. Therefore, it is possible to suppress pumping noise generated when the block 4 is grounded and the air in the lateral groove 3 is compressed and released. In addition, the frequency of the pumping noise generated from each lateral groove 3 during one rotation of the tire is not regular, and the pumping noise is sufficiently reduced in combination with the randomness of the cross-sectional shape of the lateral grooves 3 arranged in the tire width direction. Can be suppressed.

The present invention is not limited to the configuration described in the above embodiment, and various modifications can be made.

In the above embodiment, the convex portions 5 are formed on both side surfaces 7 of the lateral groove 3, but the concave portions 9 may be formed. As shown in FIG. 7, the recess 9 gradually separates both side surfaces 7 from the upper surface side edge 4a of the block 4 toward the inner diameter of the tire, and becomes the most separated state in the central portion in the depth direction, and then the groove. The groove bottom 8 can be formed so as to have the same width as the upper surface side edge 4a by gradually approaching the bottom. With this configuration as well, pumping noise can be sufficiently suppressed. However, for the following reasons, forming the convex portions 5 on both side surfaces 7 of the lateral groove 3 is more effective in suppressing pumping noise.

That is, in the case of FIG. 3 in which the side surface position of the lateral groove 3 in FIG. 2 is provided with a convex portion 5 and protrudes inward, and in the case of FIG. 7 in which a concave portion 9 is provided and recessed outward, the lateral groove 3 Compare the amount of change in the cross-sectional area of. In FIGS. 3 and 7, the shapes of the convex portion 5 and the concave portion are in a plane-symmetrical relationship with the side surface 7 of FIG. 2 as the center. Here, the dimensions of each part are set as shown in FIGS. 3 and 7, and it is assumed that the block 4 is compressed by 1 mm in the tire inner diameter direction (when the tire actually touches the road surface, the compression is larger than this). Although it receives force, it is assumed to be slightly deformed here to simplify the calculation.) In FIG. 3, the amount of change ΔS1 in the cross-sectional area is given by the following equation.

On the other hand, in FIG. 7, the amount of change ΔS2 in the cross-sectional area is given by the following equation.

を満足するとき、（数１）及び（数２）から、常にΔＳ１＜ΔＳ２となる。つまり、図７に比べて図３の方が横断面積すなわち体積の変化量が小さく、ポンピングノイズを抑制することができる。 And the following formula

When the above is satisfied, ΔS1 <ΔS2 always from (Equation 1) and (Equation 2). That is, the cross-sectional area, that is, the amount of change in volume is smaller in FIG. 3 than in FIG. 7, and pumping noise can be suppressed.

In the above embodiment, for convenience of explanation, a pneumatic tire having a tread pattern having a simple shape in which the blocks 4 are aligned in the tire circumferential direction and the tire width direction has been described, but various tread patterns modified from those shown in the drawings may be used. Even a pneumatic tire having a tire can be adopted in the same manner. For example, the blocks 4 arranged in the tire circumferential direction may be displaced in the tire width direction. Further, the blocks 4 arranged in the tire width direction may also be displaced in the tire circumferential direction.

In the above embodiment, the cross-sectional shape of the lateral groove 3 is set to 5 types, but 5 or more types may be used. Further, the shape of the convex portion 5 formed on the side surface 7 of the lateral groove 3 does not have to be uniformly formed in the tire radial direction. Then, as long as the width dimension of the lateral groove 3 is increased or decreased and the amount of change in the volume of the groove space when the block 4 comes into contact with the road surface is suppressed, any form can be adopted.

1 ... Tread part 2 ... Main groove 3 ... Horizontal groove 4 ... Block 4a ... Top side edge 5 ... Convex part 6a, 6b ... Inclined surface 7 ... Side surface 8 ... Groove bottom 9 ... Concave

Claims (5)

A pneumatic tire having a plurality of blocks formed in a tread portion by a main groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction.
The block has a cross section orthogonal to the extension direction of the lateral groove formed in the same cross-sectional shape over the entire lateral groove, and in the cross section, a central portion in the depth direction is formed on both side surfaces constituting the lateral groove. A convex portion having a triangular cross section that protrudes most in the opposite direction is formed, whereby the distance between the two side surfaces is increased or decreased in the tire radial direction .
The cross-sectional shape of the lateral groove, which is orthogonal to the extension direction of the lateral groove, gradually narrows from the upper surface side edge toward the tire inner diameter direction, becomes the narrowest at the central portion in the depth direction, and then gradually narrows toward the groove bottom. A pneumatic tire characterized in that it becomes wider and has the same width as the upper surface side edge at the groove bottom . The first aspect of claim 1, wherein the lateral grooves between the blocks arranged side by side in the tire circumferential direction in the tread portion are composed of a plurality of types having different cross-sectional shapes in a cross section orthogonal to the extension direction of the lateral grooves. Pneumatic tires. The air according to claim 1 or 2, wherein among the lateral grooves, the lateral grooves arranged side by side in the tire width direction are composed of a plurality of types having different cross-sectional shapes of cross sections orthogonal to the extension direction of the lateral grooves. Tires with. The pneumatic tire according to any one of claims 1 to 3, wherein the lateral groove has two inclined surfaces whose side surfaces on both sides gradually approach each other from the tread surface and then gradually separate from each other. The pneumatic tire according to any one of claims 1 to 4, wherein the lateral groove is composed of a plurality of types in which the cross-sectional area of the cross section orthogonal to the tire width direction is reduced at a constant rate.

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