JP5785577B2 - Pneumatic tire - Google Patents

Description

  The present invention particularly relates to a pneumatic tire with improved heat dissipation of a tread.

  A tire mounted on a vehicle generates heat due to repeated expansion and contraction accompanying load rolling. In particular, this heat generation becomes conspicuous in the tread in contact with the road surface, and causes various failures of the tread (for example, heat separation). Therefore, the device which discharge | releases the heat | fever which generate | occur | produces in the tread of a pneumatic tire is required.

  In order to meet this need, conventionally, a pneumatic tire having a groove on the tread surface has been used. According to this tire, by providing the groove, the tread itself as a heat generation source can be reduced, the surface area of the tread can be increased, and the heat dissipation of the tread of the pneumatic tire can be enhanced.

JP 2003-205706 A

However, in the conventional pneumatic tire described above, it is necessary to increase the total capacity of the groove in order to further improve the effect of improving heat dissipation. However, if the total capacity of the groove is increased, the rigidity of the land portion is reduced. The tire wear performance and steering stability performance may be deteriorated.
Then, an object of this invention is to provide the pneumatic tire which improved the heat dissipation of the tread, suppressing the increase in the total capacity | capacitance of a groove | channel.

The gist of the present invention is as follows.
In the pneumatic tire of the present invention, narrow grooves extending in the tire circumferential direction and having a groove width smaller than the groove depth are provided on the tread tread surface at intervals in the tire circumferential direction. Are both ends in the land portion, and at one end of the narrow groove, among the groove wall surfaces of the narrow groove facing in the tire circumferential direction, from one end of the narrow groove to the other end of the narrow groove An inflow portion is provided that extends in the tire circumferential direction only, communicates with the narrow groove at one end and terminates at the other end only on the groove wall surface on the end side of the tire circumferential component of the first vector toward Here, the inflow portion is provided on both of the groove wall surfaces of the narrow groove facing in the tire circumferential direction , and the depth gradually increases from the other end of the inflow portion toward one end of the inflow portion. , between adjacent in the circumferential direction of the tire, it combined the thin groove and the inlet portion In the tire circumferential direction outermost end of one of the parts, the one on the other part side and the one on the one part side of the tire circumferential direction outermost end of the other part, They are separated in the tire circumferential direction.
With the above configuration, since the projected length in the tire circumferential direction of the portion including the narrow groove and the inflow portion can be made relatively small, the position of the seam of the mold for tread molding corresponds to the position of the narrow groove or the inflow portion. This is easy to avoid, and burrs are less likely to occur on the narrow groove and / or the inflow portion. Therefore, according to the pneumatic tire of the present invention, the heat dissipation of the tread can be enhanced while suppressing an increase in the total capacity of the grooves. Moreover, if it is set as the said structure, the effect which improves the heat dissipation of a tread can be heightened further.
The “tread surface” is a tire that comes into contact with the road surface when the tire that is assembled to the applicable rim and filled with the specified internal pressure is rolled with a load corresponding to the maximum load capacity applied. Means the outer peripheral surface of the entire circumference. Here, the “applicable rim” is a standard rim defined in the following standard according to the tire size (specified as “Design Rim” in YEAR BOOK of the following TRA. “Measuring Rim” in STANDARDDS MANUAL of the following ETRTO. )), And “specified internal pressure” means the air pressure specified in accordance with the maximum load capacity in the following standards, and “maximum load capacity” means that the tire is loaded in accordance with the following standards. Refers to the maximum mass allowed. The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “THE TIRE AND RIM ASSOCIATION INC. (TRA)” “YEAR BOOK” In Europe, it is “STANDARDS MANUAL” of “The European Tire and Rim Technical Organization (ETRTO)”, and in Japan it is “JATMA YEAR BOOK” of “Japan Automobile Tire Association (JATMA)”.
The “groove depth (of the narrow groove)” refers to the largest depth in the tire radial direction of the narrow groove, and the “(groove width) of the groove” refers to the tire of the narrow groove. Refers to the width in the circumferential direction.
Furthermore, unless otherwise specified, the dimensions of the pneumatic tire of the present invention refer to the dimensions when the tire is mounted on an applicable rim, set to a specified internal pressure, and in a no-load state.

  In the pneumatic tire of the present invention, the tire of the first vector has a tire circumferential direction projection length Lx of the portion including the narrow groove and the inflow portion that is the same as the position of the inflow portion in the tire width direction position. Smaller than the tire circumferential projection length Lx ′ of the combined portion of the narrow groove and the virtual inflow portion when the virtual inflow portion is provided in the groove wall surface on the starting point side of the circumferential direction component It is preferable. If it is the said range, the said effect of improving the heat dissipation of a tread will be easier to be acquired.

  Furthermore, in the pneumatic tire of the present invention, the distance along the extending direction of the narrow groove from one end of the narrow groove to the position of the inflow portion is 0 to 0 of the extending length of the narrow groove. 35% is preferable. If it is the said structure, the said effect of improving the heat dissipation of a tread will be acquired more easily.

  Furthermore, in the pneumatic tire of the present invention, it is preferable that the inflow portion is provided at one end of the narrow groove. If it is the said structure, the said effect of improving the heat dissipation of a tread will be further easy to be acquired.

  Furthermore, in the pneumatic tire of the present invention, it is preferable that an angle θ2 formed by the first vector and a second vector directed from one end of the inflow portion to the other end of the inflow portion is less than 90 °. . If it is the said structure, the said effect of improving the heat dissipation of a tread will be further easy to be acquired.

  Furthermore, in the pneumatic tire of the present invention, the angle θ2 is preferably 50 to 70 °. If it is the said structure, the said effect of improving the heat dissipation of a tread will be further easy to be acquired.

  According to the pneumatic tire of the present invention, the heat dissipation of the tread can be improved while suppressing an increase in the total capacity of the grooves.

(A) is a partial expanded view showing the tread surface of the pneumatic tire of an example of the present invention, (b) cuts the tire shown in (a) along the line AA extending in the tire circumferential direction. It is sectional drawing when doing. (A) is an expansion of narrow grooves and inflow portions ((i) to (iv)) that can be used in the tire shown in FIG. 1, and narrow grooves and virtual inflow portions ((i)) used in the tire of the comparative example. It is a figure, (b) is a figure which shows the 1st vector which makes one end of the narrow groove | channel shown to (a) a start point, and the other end is an end point, (c) is shown to (a). In (i)-(iv), it is a figure which shows the 2nd vector which makes one end of an inflow part a starting point, and makes the other end an end point with the 1st vector shown in (b). (A) is an enlarged view of a narrow groove and an inflow portion that can be used in the tire shown in FIG. 1, (b) is a diagram showing a first vector for the narrow groove shown in (a), (c) (A) is a figure which shows the 2nd vector about the fine groove shown to (a) with the 1st vector shown to (b). FIG. 2 is an enlarged view of a narrow groove and an inflow portion that can be used in the tire illustrated in FIG. 1 when inflow portions are provided on both of the groove wall surfaces of the narrow groove.

Hereinafter, embodiments of the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1A is a partial development view showing a tread surface of a pneumatic tire according to an example of the present invention.
A pneumatic tire 1 (hereinafter also referred to as “tire 1”) according to an example of the present invention includes a pair of central circumferential grooves 13 and 13 that extend along the tire circumferential direction across the tire equator C on the tread tread surface 2. A pair of lateral circumferential grooves 14 and 14 extending along the tire circumferential direction are provided outside the central circumferential grooves 13 and 13 in the tire width direction. Further, the tread tread surface 2 extends along the tire width direction, and extends along the tire width direction with an intermediate width direction groove 15 that communicates with the central circumferential groove 13 and the lateral circumferential groove 14. A lateral width direction groove 16 that communicates with the groove 14 and extends to the tread grounding end TG is provided.
The tread ground contact end TG refers to the tire width direction end of the tread surface.

  Further, the tire 1 is defined by a central circumferential groove 13 and is defined by a rib-shaped central land portion 17 including the tire equator C, a central circumferential groove 13, a lateral circumferential groove 14, and an intermediate width direction groove 15. And a block-shaped side land portion 19 defined by the side circumferential groove 14, the side width direction groove 16, and the tread ground contact end TG.

The tire 1 is provided with a narrow groove 3 extending at an incline in the tire circumferential direction on the rib-shaped central land portion 17 on the tread tread 2 and having both ends 3 a and 3 b terminating in the rib-shaped central land portion 17.
FIG. 1B shows a cross-sectional view of the tire shown in FIG. 1A taken along line AA extending in the tire circumferential direction. Here, as shown in FIG. 1B, the narrow groove 3 has a groove width w3 that is smaller than the groove depth d3.
In the tire 1, the narrow grooves 3 are provided at a constant pitch Lp in the tire circumferential direction.

Further, in the tire 1, an inflow portion 4 extending in the tire circumferential direction is provided on the groove wall surface 3 w (3 we) of the narrow groove 3. The inflow portion 4 communicates with the narrow groove 3 at one end 4a and terminates at the other end 4b.
“Extending in the tire circumferential direction” does not mean strictly extending in the tire circumferential direction, but means extending in a direction having a component in the tire circumferential direction.

The enlarged view of the narrow groove 3 and the inflow part 4 which can be provided in the tire 1 is shown to Fig.2 (a) (i)-(iv). Hereinafter, unless otherwise noted, the description in the developed view showing the tread surface is used.
Here, as shown in FIG. 2B, a vector from one end 3a of the narrow groove 3 toward the other end 3b of the narrow groove 3 is defined as a first vector V1. At this time, in the tire 1, as shown in FIGS. 2 (a), (ii) to (iv), at one end 3 a of the narrow groove 3, the groove wall surfaces 3 we, 3 ws ( 3w), an inflow portion 4 extending in the tire circumferential direction is provided on the groove wall surface 3we of the narrow groove 3 on the end point V1ce side of the tire circumferential component V1c of the first vector V1, that is, in the tire circumferential direction. An inflow portion is provided in the groove wall surface 3we of the narrow groove 3 on the opposite side of the groove wall surface 3we, 3ws (3w) of the groove wall 3 opposite to the side facing the tire circumferential component V1c of the first vector V1. It has been.
In the pneumatic tire of the present invention, the inflow portion 4 is provided at one end 3ap of the narrow groove 3 as shown in FIGS. 2 (a) (i) to (iv). In the tire 1, the inflow portion 4 extends from the groove wall surface 3w (3we) in a direction opposite to the direction of the tire circumferential component V1c of the first vector V1.

  In the example shown in FIGS. 2 (a) (i) to (iv), the first vector V1 starts from the midpoint X of the line segment extending in the tire circumferential direction that forms one end 3a of the narrow groove 3, In the pneumatic tire of the present invention, the first vector V1 is one of the narrow grooves 3, although the middle point Y of the line segment extending in the tire circumferential direction that forms the other end 3b of the narrow groove 3 is the end point. It is also possible to use a vector whose starting point is the outermost point in the tire width direction at the end 3ap and whose end point is the outermost point in the tire width direction at the other end 3bp of the narrow groove 3.

When the tire rolls, wind flows in a direction opposite to the tire rotation direction. This wind flows into a groove provided on the tread surface and then flows out, so that heat of the tread is released and the tread is cooled.
Here, when the width of the groove is increased, the amount of wind flowing into the groove increases and the effect of cooling the tread increases, but the rigidity of the land portion decreases and the wear resistance and steering stability of the tire decrease. . Decreasing the width of the groove reduces the rigidity of the land and suppresses the wear resistance and steering stability of the tire, but reduces the amount of wind flowing into the groove to cool the tread. The effect is weakened.

  In the tire 1 of the present invention in which an inflow portion is provided in addition to the narrow groove having a relatively small groove width, wind is easily taken into the narrow groove 3 through the inflow portion 4 during tire rolling. For this reason, the amount of wind flowing into the narrow groove 3 increases. Therefore, according to the pneumatic tire of the present invention, an effect of cooling the tread due to the narrow groove and the inflow portion can be obtained.

Hereinafter, the effect of the tire 1 of an example of the present invention will be described.
In the tire as a comparative example of the tire 1 of the example of the present invention in which the narrow groove 3 and the inflow portion 4 shown in FIGS. 2A and 2I are provided, the same position in the tire width direction as the position of the inflow portion 4 of the tire 1 In FIG. 1, an inflow portion is provided on the groove wall surface 3ws of the narrow groove 3 on the side of the starting point V1cs of the tire circumferential direction component V1c of the first vector V1 (indicated by a virtual inflow portion 4 ′ in FIG. 1A).
Here, in one end portion 3ap of the narrow groove 3, the inflow portion 4 is provided on the groove wall surface 3we of the narrow groove 3 on the end point V1ce side of the tire circumferential direction component V1c of the first vector V1. The tire circumferential projection length Lx (typically shown in FIGS. 2A and 2I) of the portion of the tire 1 including the narrow groove 3 and the inflow portion 4 is a tire circumferential component of the first vector V1. Tire circumferential direction projection length of the combined portion of the narrow groove 3 and the inflow portion 4 in the pneumatic tire of the comparative example in which the virtual inflow portion 4 ′ is provided on the groove wall surface 3ws of the narrow groove 3 on the side of the starting point V1cs of V1c It is smaller than the length Lx ′ (shown in FIGS. 2A and 2I).
Note that the position of the inflow portion 4 is a point 4ao and the narrowest groove on the line forming one end 4a of the inflow portion 4 that is closest to one end 3a of the narrow groove 3 as shown in FIG. 3 indicates the midpoint P with the point 4aoi close to the other end 3b. The position of the virtual inflow portion 4 ′ indicates the point P ′ determined in the same manner (see FIG. 2 (i)). Here, a straight line passing through the point P for the tire 1 of the present invention and the point P ′ for the pneumatic tire of the comparative example is parallel to the tire circumferential direction, that is, the position of the inflow portion 4 and the virtual inflow The position in the tire width direction is the same as the position of the portion 4 ′.
A pneumatic tire is generally manufactured by vulcanization using a tire molding die. Here, the tread is molded by arranging a plurality of molds for molding a tread over the entire circumference of the tire (using a sector divided in the tire circumferential direction). A small amount of tread rubber may leak to the outside of the mold at the joint of the mold for tread molding. In this case, the tread surface of the vulcanized pneumatic tire is locally burr (excess A new rubber). When the position of the seam of the tread molding die corresponds to the position of the narrow groove and / or the inflow portion provided on the tread surface, burrs are generated on the narrow groove and / or the inflow portion, and the narrow groove And / or a part of the inflow portion is buried. As a result, when narrow grooves having the same number of inflow portions are provided on the tread surface, the position of the seam of the tread molding die becomes smaller as the projected length in the tire circumferential direction of the portion including the narrow grooves and the inflow portions is smaller. However, it is easy to avoid hitting the position of the narrow groove or the inflow portion, and the disturbance of the shape of the narrow groove and the inflow portion due to the burr is reduced.
Therefore, according to the tire 1 of the example of the present invention having a relatively small projection length Lx in the tire circumferential direction of the combined portion of the narrow groove 3 and the inflow portion 4, the tread by the narrow groove 3 and the inflow portion 4 is cooled. It is easy to obtain the effect.

Moreover, in the tire 1 of an example of the present invention, when the direction of the tire circumferential direction component V1c of the first vector V1 (the direction from one end of the inflow portion toward the other end of the inflow portion) is the tire rotation direction. Has the following effects. In one end portion 3 ap of the narrow groove 3, it flows into the inflow portion 4 from the other end 4 b of the inflow portion 4 that opens to the tread surface 2, and the narrow groove from one end 4 a of the inflow portion 4 that communicates with the narrow groove 3. The air that has flowed into 3 flows from one end 3ap of the narrow groove 3 to the other 3 bp of the narrow groove 3 over most of the extending length L3 of the narrow groove 3. Thereby, the area | region inside the narrow groove 3 through which air flows can be enlarged comparatively.
In the tire 1 of the example of the present invention, the direction opposite to the direction of the tire circumferential direction component V1c of the first vector V1 (the direction from the other end of the inflow portion toward one end of the inflow portion) is In the case of the rotational direction, the air that has flowed into the narrow groove 3 at the other end 3 bp of the narrow groove 3 flows out from the inflow portion 4 provided at the one end 3 ap of the narrow groove 3. Can do.
Therefore, according to the tire 1 of the example of the present invention, it is easy to obtain the effect of cooling the tread by the narrow groove 3 and the inflow portion 4.

Therefore, according to the pneumatic tire of this invention, the heat dissipation of a tread can be improved.
Moreover, according to the pneumatic tire of the present invention, as described above, since burrs are hardly generated on the narrow groove and / or the inflow portion, the manufacturing efficiency of the tire can be improved.

In the tire 1 according to an example of the present invention, as illustrated in FIG. 1, the outermost circumferential direction of one portion 21 is between the portions 21 and 22 including the two narrow grooves 3 and the inflow portion 4 adjacent to each other in the tire circumferential direction. Of the ends 21e1, 21e2, the one 21e2 on the other portion 22 side and the other portion 22 of the outermost circumferential ends 22e1, 22e2 on the one portion 21 side are separated in the tire circumferential direction That is, the tire circumferential projection length Li> 0 of the line segment 21e2-22e1. By separating the tire circumferential direction outermost ends 21e2 and 22e1 in the tire circumferential direction, it is possible to avoid the position of the seam of the tread molding die from hitting the position of the narrow groove 3 or the inflow portion 4.
1, the tire circumferential direction outermost end 21e2 is one end 3a of the narrow groove 3, and the tire circumferential direction outermost end 22e1 is the other end 3b of the narrow groove 3. However, in the pneumatic tire of the present invention, the tire circumferential direction outermost ends 21e2 and 22e1 may be the other end of the inflow portion 4 without being limited thereto.

As described above, in the pneumatic tire of the present invention, the distance M1 along the extending direction of the narrow groove 3 from the one end 3a of the narrow groove 3 to the position of the inflow portion 4 is the extension length of the narrow groove 3. It is preferable that it is 0 to 35% of the length L3.
In this case, the extended length L3 of the narrow groove 3 from the position where the air flowing into the narrow groove 3 from the inflow portion 4 is closer to one end 3a of the narrow groove 3 to the position closer to the other end 3b of the narrow groove 3 is provided. It flows over almost the majority of Thereby, the area | region inside the narrow groove 3 through which air flows can be enlarged further. Therefore, it is easy to obtain the above effect of improving the heat dissipation of the tread. Moreover, reduction of the distance of the tire circumferential direction between the narrow grooves 3 adjacent to the tire circumferential direction can be suppressed.

Here, the distance M1 along the extending direction of the narrow groove 3 from one end 3a of the narrow groove 3 to the position of the inflow portion 4 is the narrow groove 3 between the midpoint P and the point X. The distance along the extending direction of
Further, the extending length L3 of the narrow groove 3 indicates a linear distance between the point X and the point Y, that is, the length of the first vector V1.

  Further, as described above, as shown in FIGS. 2 (a), (ii) to (iv), in the tire 1, the inflow portion 4 is provided at one end 3 a of the narrow groove 3. The air flowing into the groove 3 flows from one end 3a of the narrow groove 3 to the other end 3b of the narrow groove 3 over almost the entire extending length L3 of the narrow groove 3. Thereby, the area | region inside the narrow groove 3 through which air flows can be enlarged further. Therefore, it is easier to obtain the above effect of improving the heat dissipation of the tread. Further, the reduction in the distance in the tire circumferential direction between the narrow grooves 3 adjacent in the tire circumferential direction can be minimized.

Here, “the inflow portion 4 is provided at one end 3 a of the narrow groove 3” means a point 4 aoo of the line forming the one end 4 a of the inflow portion 4 closest to the one end 3 a of the narrow groove 3. This means that a point on the outer side in the tire width direction at one end 3ap of the narrow groove 3 coincides.
In the tire 1, since one end 3a of the narrow groove 3 is a straight line parallel to the tire circumferential direction, any point on 3a is located on the outer side in the tire width direction at one end 3ap of the narrow groove 3. Can be a point.

Here, as shown in FIG. 2C, a vector directed from one end 4a of the inflow portion 4 provided at one end 3ap of the narrow groove 3 to the other end 4b of the inflow portion 4 is expressed as a second vector V2. And
2 (c) (i) to (iv) show the first vector V1 and the second vector V2 for the narrow groove 3 and the inflow portion 4 shown in FIGS. 2 (a), (i) to (iv), respectively.
The second vector V2 is a line between one end 4a of the inflow portion 4 and a point 4aoo closest to one end 3a of the narrow groove 3 and a point 4aoi closest to the other end 3b of the narrow groove 3. The middle point P is the starting point V2s, and the line 4boo closest to one end 3a of the narrow groove 3 and the point 4boi closest to the other end 3b of the narrow groove 3 of the line forming the other end 4b of the inflow portion 4 A vector having the middle point Q as the end point V2e is indicated.

  At this time, in the tire 1, as shown in FIGS. 2 (c) and (iv), the angle θ2 formed by the first vector V1 and the second vector V2 is preferably less than 90 ° (acute angle). That is, in the tire 1, the narrow groove 3 and the inflow portion 4 shown in FIGS. 2 (a) and (iv) are compared with the narrow groove 3 and the inflow portion 4 shown in FIGS. 2 (a) (i) to (iii). It is preferable to use it.

If the angle θ2 is an acute angle, at one end 3 ap of the narrow groove 3, the inflow portion that flows into the inflow portion 4 from the other end 4 b of the inflow portion 4 that opens to the tread surface 2 and communicates with the narrow groove 3. Rather than the air flowing into the narrow groove 3 from one end 4a of the groove 4 toward the end 3bp toward the narrow groove 3 from one end 3ap of the narrow groove 3, one end of the narrow groove 3 Concentrate on 3ap. The air concentrated on one end 3ap of the narrow groove 3 flows inward in the tire radial direction at the one end 3ap of the narrow groove 3, reaches the groove bottom 3bo of the narrow groove 3, and then the air , Flows from one end 3ap of the narrow groove 3 toward the other end 3bp of the narrow groove 3, reaches the other end 3bp of the narrow groove 3, and air flows to the other end 3bp of the narrow groove 3. It flows toward the outside in the tire radial direction at the portion 3 bp. In this way, air flows through the deep part of the narrow groove 3 and then flows out to the tread surface 2. Here, the generation of heat in the tread is remarkable in the tread portion on the inner side in the tire radial direction as compared with the tread portion on the outer side in the tire radial direction, and even when air flows in the deep part of the narrow groove 3, The heat generated in the tread can be released more effectively.
Therefore, if the angle θ2 is less than 90 °, the above effect of improving the heat dissipation of the tread is further easily obtained.

Here, the angle θ2 is preferably 50 to 70 °.
When the angle θ2 is in the above range, the above effect of improving the heat dissipation of the tread can be further easily obtained.

  Further, in the pneumatic tire of the present invention, one end of the narrow groove 3 shown in FIG. 3A is obtained by replacing one end and the other end of the narrow groove 3 shown in FIG. The groove wall surface 3we of the narrow groove 3 on the end V1ce side of the tire circumferential direction component V1c of the first vector V1 among the groove wall surfaces 3we and 3ws (3w) of the groove wall 3 facing in the tire circumferential direction at the end 3a In addition, an inflow portion 4 extending in the tire circumferential direction can be provided. FIG. 3B shows the first vector V1 in this case, and FIG. 3C shows the second vector in this case.

  The preferred embodiment of the inflow portion 4 can be the same as the preferred embodiment of the inflow portion 4.

  And in the pneumatic tire of this invention, as shown in FIG. 4, it is preferable that the inflow part 4 is provided in both the groove wall surfaces 3w of the narrow groove 3 which opposes a tire circumferential direction.

If the inflow portions 4 are provided on both the groove wall surfaces 3 w of the narrow groove 3, the air flowing into the narrow groove 3 from the inflow portion 4 provided on the one end 3 ap side of the narrow groove 3 is transferred to the other side of the narrow groove 3. It can flow out from the inflow part 4 provided in the edge part 3bp side. Therefore, the heat dissipation of the tread can be further enhanced.
Moreover, if the inflow part 4 is provided, the effect of improving the heat dissipation of the tread can be obtained regardless of whether the direction of the tire circumferential direction component of the first vector V1 or the opposite direction is the rotation direction of the tire. be able to.

  In the tire 1, as shown in FIG. 1 (a), the narrow grooves 3 are provided at a constant pitch Lp in the tire circumferential direction. The grooves only need to be provided at intervals in the tire circumferential direction. If the narrow grooves are provided at intervals in the tire circumferential direction, the position of the seam of the mold for tread molding can be avoided from hitting the position of the narrow groove or the inflow portion. It is possible to prevent burrs from being generated. Therefore, the effect of improving the heat dissipation of the tread can be obtained.

In the pneumatic tire of the present invention, if the narrow groove 3 and the inflow portion 4 are provided anywhere on the tread surface 2, the effect of enhancing the heat dissipation of the tread can be obtained.
In the tire 1, the narrow groove 3 and the inflow portion 4 are provided in the rib-shaped central land portion 17 including the tire equatorial plane CL. Here, in the rib-shaped central land portion 17, the contact pressure at the time of tire rolling is particularly high, and the expansion and contraction of the tread rubber is particularly large. Therefore, if the narrow groove 3 and the inflow portion 4 are provided in the rib-shaped central land portion 17, the above-described effect of improving the heat dissipation of the tread by the narrow groove 3 and the inflow portion 4 can be easily obtained.

  In the pneumatic tire of the present invention, the smaller angle θ1 (typically shown in FIG. 1A) of the angle formed between the extending direction of the narrow groove 3 and the tire circumferential direction is 45 to 70 °. Preferably, the angle is 55 to 65 °. If it is the said range, the inflow of the wind to the narrow groove 3 is securable.

In the tire 1, it is preferable that the ratio (w4 / w3) of the tire circumferential direction length w4 (see FIG. 1B) of the inflow portion 4 to the groove width w3 of the narrow groove 3 is 3-7. If w4 / w3 is within the above range, it is possible to achieve both the rigidity of the land portion where the narrow groove 3 and the inflow portion 4 are provided and the improvement of the heat dissipation of the tread.
Further, the ratio (d4 / d3) of the depth d4 of the inflow portion 4 (see FIG. 1B) to the groove depth d3 of the narrow groove 3 is preferably 1/7 to 1/3. If d4 / d3 is within the above range, it is possible to achieve both the rigidity of the land portion where the narrow groove 3 and the inflow portion 4 are provided and the improvement of the heat dissipation of the tread.

In the tire 1, as shown in FIGS. 2 (a), (i) to (iii), the shape of the inflow portion 4 on the tread surface 2 is parallel including a pair of sides parallel to the extending direction of the narrow groove 3. Although it is a quadrilateral, in the pneumatic tire of the present invention, the shape is not limited to this, and may be any shape.
Examples of the shape of the inflow portion 4 on the tread surface 2 include a parallelogram, trapezoid, a shape in which the tire width direction length gradually increases, a shape in which the tire circumferential direction length gradually increases, a semicircle, a triangle, and the like.

  Further, the shape of the cross section of the inflow portion 4 in a plane perpendicular to the extending direction of the narrow groove 3 is as shown in FIG. 1B, from the other end 4b of the inflow portion 4 to one end 4a of the inflow portion 4. It is preferable that the depth gradually increases toward the end of the inflow portion 4, and the depth of the inflow portion 4 is maximized at one end 4 a of the inflow portion 4.

  In the tire 1, as shown in FIG. 1 (b), the shape of the cross section by a plane perpendicular to the extending direction of the narrow groove 3 of the inflow portion 4 is such that one end 4 a and the other end 4 b of the inflow portion 4 are formed. Although it is a straight line that connects, in the pneumatic tire of the present invention, the shape is not limited to this, and may be any shape.

The tire 1 has a tread pattern having a rib-like land portion and a block-like land portion. However, the tread pattern of the pneumatic tire of the present invention is not limited to this and may be any pattern. .
Moreover, although both ends 3a and 3b of the narrow groove terminate in the rib-shaped central land portion 17, in the pneumatic tire of the present invention, at least one end of the narrow groove has other grooves (for example, circumferential grooves). ) May be open.

  In the tire 1, the narrow groove 3 and the inflow portion 4 are provided in the rib-shaped central land portion 17 including the tire equator C. However, in the pneumatic tire of the present invention, the narrow groove 3 and the inflow portion 4 are provided on the tread surface. 2 may be provided anywhere.

  The pneumatic tire of the present invention is particularly preferably used for construction vehicle tires and truck / bus tires having a relatively large tread.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to the following Example at all.

  In this example, a vulcanized tire having a narrow groove and an inflow portion and having the specifications shown in Table 1 is formed by molding a tire using a normal technique in the tire industry and then vulcanizing. Produced. For vulcanization, a vulcanizer for vulcanizing the tread using a plurality of molds was used.

  The prepared tire was mounted on an applicable rim (53 / 80R63) defined in the JATMA standard and assembled with the rim to obtain an internal pressure of 600 kPa. And the wind which flows to a tire peripheral direction was given to this tire. Here, a film heater is provided on the groove wall on the lee side of the narrow groove of the tire to heat the narrow groove, and this heat is measured at a point near the center of the groove wall on the windward side of the narrow groove. The thermal conductivity inside the narrow groove was evaluated. Specifically, an index for relative evaluation with the evaluation result of Comparative Example 1 as 100 was calculated. It shows that the effect which improves the heat dissipation of a tread is so high that an index | exponent is large. Detailed conditions and results are shown in Table 1.

By comparing with Comparative Example 1 and Reference Example 1, burrs on the narrow grooves and / or the inlet has been shown to be less likely to occur. By comparing Reference Example 3 with Reference Examples 1, 2, and 4, it was shown that the effect of increasing the heat dissipation of the tread is particularly high.

  According to the pneumatic tire of the present invention, the heat dissipation of the tread can be improved while suppressing an increase in the total capacity of the grooves. The pneumatic tire of the present invention is particularly suitably used for construction vehicle tires and truck / bus tires.

DESCRIPTION OF SYMBOLS 1; Pneumatic tire, 2; Tread surface, 3; Narrow groove, 3a (3e); One end of a narrow groove, 3b (3e); The other end of a narrow groove, 3ap (3ep); One of a narrow groove End, 3 bp (3 ep); the other end of the narrow groove, 3 bo: the groove bottom of the narrow groove, 3 w: the groove wall surface of the narrow groove, 3 we (3 w): on the end point side of the tire circumferential component of the first vector , Groove wall surface of the narrow groove, 3ws (3w); groove wall surface of the narrow groove on the starting point side of the tire circumferential component of the first vector, 4; inflow portion, 4 ′; virtual inflow portion, 4a (4e); 4b (4e); the other end of the inflow part, 4aoo; the point closest to one end of the narrow groove of the line forming one end of the inflow part, 4aoi; one end of the inflow part The point closest to the other end of the narrow groove of the line forming the line 4boo; at the one end of the thinnest groove of the line forming the other end of the inflow portion There point, 4Boi; lines forming the other end of the inlet portion, a point near the other end of the most narrow grooves, 21, 22; part of the combined narrow groove and the inlet portion adjacent to the tire circumferential direction, 21E1,21e2 22e1, 22e2; tire circumferential direction outermost end of the combined portion of the narrow groove adjacent to the tire circumferential direction and the inflow portion, d3: groove depth of the narrow groove, d4: depth of the inflow portion, w3: of the narrow groove Groove width in the tire circumferential direction, w4: tire circumferential direction length of the inflow portion, C: tire equator, CL: tire equator plane, M1: extension of the narrow groove from one end of the narrow groove to the position of the inflow portion Distance along the direction, L3: Extension length of the narrow groove, Li: Projected length in the tire circumferential direction, Lx: Projected length in the tire circumferential direction of the combined portion of the narrow groove and the inflow portion, Lx ′: Fine groove and Tire circumferential projection length of the combined virtual inflow part, P; point 4ao and point 4ao Q: midpoint between point 4boo and point 4boi, Tw: tread contact width, TG: tread contact end, V1: first vector, V1c: tire circumferential component of V1, V1ce; end point of V1c, V1cs: start point of V1c, V2: second vector, V2e: end point of V2, V2s: start point of V2, θ1: angle formed by the extending direction of the narrow groove and the tire circumferential direction, θ2: angle formed by V1 and V2

Claims (6)

On the tread surface, narrow grooves extending in the tire circumferential direction and having a groove width smaller than the groove depth are provided at intervals in the tire circumferential direction,
The narrow groove terminates in the land at both ends ,
At one end of the narrow groove,
Of the groove wall surfaces of the narrow grooves facing in the tire circumferential direction, only on the groove wall surface on the end side of the tire circumferential direction component of the first vector from one end of the narrow groove toward the other end of the narrow groove An inflow portion extending in the tire circumferential direction, communicating with the narrow groove at one end and terminating at the other end,
Here, the inflow portion is provided on both of the groove wall surfaces of the narrow groove facing in the tire circumferential direction , the depth gradually increases from the other end of the inflow portion toward one end of the inflow portion,
In the portion between the narrow groove and the inflow portion adjacent to each other in the tire circumferential direction,
A tire circumferential direction includes a tire circumferential direction outermost end of one part on the other part side and a tire circumferential outermost end of the other part on the one part side. Spaced apart,
A pneumatic tire characterized by that.   The groove in the tire circumferential direction projection length Lx of the combined portion of the narrow groove and the inflow portion is at the start side of the tire circumferential direction component of the first vector at the same tire width direction position as the position of the inflow portion. In the case where a virtual inflow portion is provided on the wall surface, it is smaller than the tire circumferential direction projection length Lx ′ of the combined portion of the narrow groove and the virtual inflow portion. The described pneumatic tire.   The distance along the extending direction of the narrow groove from one end of the narrow groove to the position of the inflow portion is 0 to 35% of the extending length of the narrow groove, The pneumatic tire according to claim 1 or 2.   The pneumatic tire according to claim 1, wherein the inflow portion is provided at one end of the narrow groove.   5. The angle θ <b> 2 formed by the first vector and a second vector directed from one end of the inflow portion to the other end of the inflow portion is less than 90 °. A pneumatic tire according to claim 1.   The pneumatic tire according to claim 5, wherein the angle θ2 is 50 to 70 °.

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