JP6635779B2 - Pneumatic tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a pneumatic tire and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, as a pneumatic tire, a pneumatic tire in which a sipe having both ends closed in a block and a through hole penetrating the block and the sipe and opening in a lateral groove at both ends is known (for example, Patent Document 1) 1).

  However, in the conventional pneumatic tire, in order to increase the amount of water that can be sucked into the sipe, a flow of air is generated in the through hole. That is, this configuration is not intended to enhance drainage in the lateral groove or to suppress generation of pumping noise.

JP 2008-1260 A

  An object of the present invention is to provide a pneumatic tire capable of suppressing pumping noise and improving drainage, and a method of manufacturing the same.

The present invention, as means for solving the above problems, the bets tread portion, the pneumatic having a plurality of main grooves extending in the tire circumferential direction, a plurality of blocks formed by a plurality of lateral grooves extending in the tire width direction a tire, before Symbol block, without the main groove and said lateral groove opening, a closing groove extending from the top surface to the tire inner diameter direction, respectively formed on side surfaces of the blocks constituting the lateral grooves, said closure and a recess communicating with the groove, are communicating path is formed for communicating between the lateral grooves on both sides of the blocks before and Symbol closed groove by said recess, said closure groove, the traveling direction front side in the tire circumferential direction A pneumatic tire having an expansion portion having a cross-sectional area gradually increasing toward a rear side in a traveling direction .

With this configuration, when traveling on a wet road surface, water in the lateral groove on the traveling direction R side (front side) passes through the communication path and flows into the lateral groove on the traveling direction L side (rear side) . That is, the water in the lateral groove on the traveling direction R flows into the concave portion formed on the side surface thereof, passes through the closing groove, and then moves from the concave portion on the side surface constituting the lateral groove on the traveling direction L side to the lateral groove on the traveling direction L side. Spills into the interior. Therefore, drainage performance can be improved as compared with the case where no communication path is formed in the block. In addition, since the closed groove has an expanded portion having a gradually increasing cross-sectional area, drainage can be further improved. Further, when traveling on a dry road surface, the air in the lateral groove on the traveling direction R side is compressed, but can be released to the lateral groove on the traveling direction L side via the communication path. Therefore, the air in the lateral groove on the traveling direction R side is not compressed, and it is possible to reliably prevent the generation of pumping noise when leaving the road surface.

Of the recess, the opening area at the side constituting the lateral groove is preferably larger than the opening area of the communicating portion between the closed groove.

  With this configuration, the concave portion on the traveling direction R side functions as a so-called funnel, and it becomes easy to take in water in the lateral groove. In addition, the concave portion reduces the sudden change in the cross section of the flow channel between the time when water flows into the closed groove and the time when water flows out from the closed groove, and suppresses the phenomenon of water separation from the flow channel surface. A smooth flow can be realized.

The groove bottom of the closure grooves may be inclined so as to gradually deeper toward from the transverse groove in the traveling direction before the side to the lateral grooves in the traveling direction rear side.

The present invention provides a means for solving the above problems, the bets tread portion includes a plurality of main grooves extending in the tire circumferential direction, a plurality of blocks formed by a plurality of lateral grooves extending in the tire width direction a method of manufacturing a pneumatic tire, the first mold part to form a closed grooves having an extension portion the sectional area before Symbol block toward the traveling direction front side in the tire circumferential direction to the traveling direction of the rear side gradually increases When, and a second mold part forming the lateral grooves and recesses on the sides of the block, after the vulcanization molding, after the first mold element and is detached from the closure groove, the second mold A method for manufacturing a pneumatic tire is provided, wherein a part is detached from the lateral groove.

  According to the present invention, the block is formed with a communication path connecting the lateral grooves on both sides in the tire circumferential direction, so that when traveling on a wet road surface, the water in the lateral groove on the traveling direction R side is moved in the traveling direction. The water can be discharged to the lateral groove on the L side, and the drainage property can be improved. Further, when traveling on a dry road surface, the air in the lateral groove on the traveling direction R side can flow to the lateral groove on the traveling direction L side, and it becomes possible to suppress the generation of pumping noise.

It is a partial development view of the tread part of the pneumatic tire concerning this embodiment. FIG. 2A is a plan view of a block according to the first embodiment, and FIG. 2B is a cross-sectional view taken along line AA. (A) is a plan view of a block according to the second embodiment, (b) is a cross-sectional view taken along line AA, and (c) is a cross-sectional view taken along line BB. (A) is a top view of a block concerning a 3rd embodiment, and (b) is the AA line sectional view. (A) is a plan view of a block according to a fourth embodiment, and (b) is a cross-sectional view taken along line AA. (A) is a sectional view of a block according to another embodiment, and (b) is a side view thereof. (A) is a sectional view of a block according to another embodiment, and (b) is a side view thereof. It is a sectional view of a block concerning other embodiments.

  Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. The following description is merely an example in nature, and is not intended to limit the present invention, its application, or its use. Also, the drawings are schematic, and the ratios of the respective dimensions and the like are different from actual ones.

  FIG. 1 is a partially developed view of a tread portion 1 of the pneumatic tire according to the present embodiment. Although not shown, the pneumatic tire has a configuration in which a carcass is stretched between a pair of bead cores, reinforced by a belt wound around an outer peripheral side of an intermediate portion of the carcass, and has a tread portion 1 in a tire outer diameter direction. I have.

  In the tread portion 1, a plurality of blocks 4 are formed 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. As shown in FIGS. 2 to 5, each block 4 has a communication passage 7 formed by a closing groove 5 and a pair of recesses 6. Various configurations described below can be adopted for the communication path 7.

(1st Embodiment)
The configuration of the communication path 7 according to the first embodiment is as shown in FIGS.
The closing groove 5 is formed at the center position of the block 4 in the tire width direction, has a rectangular shape elongated in the tire circumferential direction, and extends in the tire inner diameter direction. The depth of the closing groove 5 is set to be equal to or less than the block height.

  The concave portions 6 are respectively opened on both side surfaces formed by the lateral grooves 3 on both sides of the block 4. That is, the concave portion 6 includes the first concave portion 8 that opens on the side surface of the block 4 on the tire traveling direction R side, and the second concave portion 9 that opens on the side surface on the tire traveling direction L side. Each concave portion 6 has a substantially hemispherical shape, and a closing groove 5 communicates with a central portion thereof. The position where each concave portion 6 is formed is a position where the circular opening on the side surface just contacts the groove bottom of the lateral groove 3.

  The pneumatic tire including the block 4 having the communication path 7 according to the first embodiment can be manufactured as follows. That is, as the mold, a mold separately provided with a first mold part 10 for forming the closed groove 5 and a second mold part 11 for forming the concave part 6 opening therewith along with the lateral groove 3 is used. I do. The first mold component 10 is formed of a plate. The second mold component 11 includes a ridge portion forming the transverse groove 3 and a convex portion 12 having a hemispherical shape projecting from the ridge portion and having a flat surface whose leading end portion is in contact with an end portion of the first mold component 10. Prepare.

  Then, when the mold is opened after vulcanization molding, the first mold part 10 is first moved, and then the second mold part 11 is moved. Thereby, the mold can be opened although both end portions of the first mold component 10 and the flat surface of the convex portion 12 of the second mold component 11 are in contact with each other. That is, when the second mold component 11 moves, the rubber of the tire component pressed by the convex portion 12 of the second mold component 11 is removed since the first mold component 10 has already moved. The one mold part 10 can be elastically deformed into a space formed by moving. In this case, what is pressed is the substantially hemispherical convex portion 12, and the amount of deformation of the rubber can be suppressed. Therefore, troubles such as cutting of the rubber do not occur.

  In the pneumatic tire formed in this manner, the opening area of the first recess 8 that opens on the side surface on the side in the traveling direction R is large. Therefore, when traveling on a wet road surface, the water that has entered the lateral groove 3 on the traveling direction R side by the first concave portion 8 can be collected smoothly. The first recess 8 is formed such that the cross-sectional area of the flow path gradually decreases toward the closed groove 5. For this reason, the water collected in the first recess 8 can smoothly flow toward the closing groove 5 without causing a separation phenomenon between the water and the inner surface of the first recess 8. The water that has passed through the closing groove 5 and reached the second concave portion 9 smoothly flows into the lateral groove 3 on the traveling direction L side without receiving flow resistance because the flow path cross-sectional area there is gradually widened. Is done.

  When the vehicle travels on a dry road surface, the blocks 4 on both sides of the lateral groove 3 on the traveling direction R are grounded and pushed in, so that the air in the lateral groove 3 on the traveling direction R is compressed. At this time, the compressed air flows into the lateral groove 3 on the traveling direction L side through the communication path 7. Therefore, even if the block 4 separates from the road surface and the lateral groove 3 on the traveling direction R side is opened to the atmosphere, no compressed air already exists in the lateral groove 3 on the traveling direction R side, so that pumping noise is reduced. It does not occur.

(2nd Embodiment)
The configuration of the communication path 7 according to the second embodiment is as shown in FIG.
The closing groove 5 has an opening shape on the upper surface of the block 4 similar to that of the first embodiment, but the inner flow path portion is formed so as to have a larger cross-sectional area than the upper surface opening of the block 4. Is different. That is, a communication region 13 is formed in the groove bottom portion of the closed groove 5, the communication region 13 being widened by an area having a semicircular cross section on both sides of the width of the upper opening. Further, both ends of the communication region 13 in the traveling direction R side and the traveling direction L side are extended portions 14. The extension part 14 is formed in a hollow shape that gradually decreases in opening cross-sectional area toward the concave part 6 and communicates with the central part of the concave part 6.

  In order to form the closed groove 5 having the above-described configuration, the first mold part 10 is formed in a plate-like shape and has a columnar portion 15 bulging in a semicircular cross section on both sides so that a lower end portion can form the communication region 13. It is constituted by having. At both ends of the columnar portion 15, projecting portions 16 whose outer diameters gradually become smaller are formed. In the vulcanization molding, the protrusion 16 of the first mold component 10 and the protrusion 12 of the second mold component 11 are in contact with each other. When the first mold part 10 is first moved when the mold is opened, the rubber of the portion corresponding to the protrusion 16 is deformed, but the protrusion dimension of the protrusion itself is not so large, and the occupied volume is also small. Since it is not so large, there is no need to worry about cracks or the like occurring in the rubber. Further, since the protruding portion 16 is provided on the cylindrical portion 15 having a larger outer diameter than the protruding portion, the protruding portion 16 has sufficient strength, and causes a problem such as deformation of the protruding portion 16 when the first mold component 10 moves. Not even.

  In the pneumatic tire provided with the communication passage 7 having the above-described configuration, since the communicating portion between the closing groove 5 and the concave portion 6 is formed by the protruding portion 16, as described above, defects such as cracks when the mold is opened also occur. It does not easily occur and has sufficient strength. Therefore, even if the block 4 is used for a long period of time, the block 4 is hardly damaged, and when traveling on a wet road surface, the flow path cross section of the communication path 7 can be sufficiently widened. It is possible to smoothly drain water to the lateral groove 3 on the traveling direction L side.

(Third embodiment)
The configuration of the communication path 7 according to the third embodiment is as shown in FIG.
The closing groove 5 is similar to the first and second embodiments in that it extends in the tire circumferential direction at the center of the upper surface of the block 4, but differs in that it is divided into two in the longitudinal direction. That is, the first closing groove 17 and the second closing groove 18 extending in the tire circumferential direction at the center of the upper surface of the block 4 are formed. Extension portions 14 are formed at both ends of the first closing groove 17 and the second closing groove 18 as in the second embodiment. The first closing groove 17 and the second closing groove 18 communicate with each other at the extension portions 14. The extension 14 of the second closing groove 18 communicates with the first recess 8, and the extension 14 of the first closing groove 17 communicates with the second recess 9.

  In order to form the closed groove 5 having the above-described configuration, the first mold component 10 is composed of a first plate-shaped body 19 and a second plate-shaped body 20. In this case, the first plate-like body 19 and the second plate-like body 20 can have substantially the same configuration as the first mold component 10 according to the second embodiment except for the size in the longitudinal direction. Then, the first plate-like body 19 and the second plate-like body 20 may be moved with a time difference provided when the mold is opened. Thus, when the mold is opened, when the first plate-shaped body 19 and the second plate-shaped body 20 are moved, there is no fear that the protrusion 16 moves to cause a defect such as a crack in the rubber. In addition, the protrusion itself does not deform.

  In the pneumatic tire provided with the communication passage 7 having the above-described configuration, the strength of the block itself can be improved by separating the closing groove 5 in addition to the same effect as in the second embodiment. Therefore, even if used for a long time, it is hard to be damaged.

(Fourth embodiment)
The configuration of the communication path 7 according to the fourth embodiment is as shown in FIG.
The closing groove 5 is formed by extending the grooves extending in the tire width direction in the tire circumferential direction. Here, the closing grooves 5 are juxtaposed at four places, and the respective closing grooves 5 are communicated with each other by the extension portions 14 as in the second or third embodiment. That is, on both surfaces of the closing groove 5, extensions 14 whose opening cross-sectional area gradually decreases from the center of the lower end, and communicate with each other with the extensions 14 extending from the adjacent closing grooves 5.

  In order to form the closed groove 5 having the above-described configuration, the first mold component 10 includes first to fourth plate-like bodies 21 to 24. A projecting portion 16 is formed at the center of the lower end on both surfaces of each of the plate members 21 to 24. Also, the plate-like members 21 to 24 may be moved with a time difference between adjacent ones when the mold is opened. For example, after the first and third plate-like members 21 and 23 are moved, the second and fourth plate-like members 22 and 24 may be moved. Accordingly, there is no fear that the rubber 16 may be damaged due to the movement of the protrusion 16, and the protrusion 16 itself is not deformed.

  In the pneumatic tire provided with the communication path 7 having the above-described configuration, in addition to the same effect as in the second embodiment, by forming a large number of the closed grooves 5, water absorption when the surface of the block 4 comes into contact with the ground during running on a wet road surface. Strength can be improved.

(Other embodiments)
Note that the present invention is not limited to the configuration described in the above embodiment, and various modifications are possible.

  In the above embodiment, the shape of the concave portion 6 opened on the side surface of the block 4 is circular. However, the shape is not limited to this, and various shapes can be adopted as shown in FIGS. It is not limited to.

  In FIG. 6, the opening shape of the concave portion 6 on the side surface of the block 4 is a triangle whose width is gradually narrowed upward. The concave portion 6 has a triangular base portion flush with the groove bottom of the closing groove 5, and the opening shape is displaced so that a portion protruding upward gradually decreases toward the closing groove 5.

  In FIG. 7, the opening shape of the concave portion 6 on the side surface of the block 4 is a semicircular shape that bulges upward in an arc shape. The concave portion 6 has a semicircular diameter portion flush with the groove bottom of the closing groove 5, and the opening shape is displaced so that a portion protruding upward gradually decreases toward the closing groove 5.

In the above embodiment, the communication path 7 is formed parallel to the upper surface of the block 4, but may be formed to be inclined as shown in FIG. Specifically, the closing groove 5 has an expanded portion 5a whose cross-sectional area gradually increases from the traveling direction R side (front side) in the tire circumferential direction toward the traveling direction L side (rear side). The groove bottom 5b of the closing groove 5 is inclined so as to gradually become deeper from the lateral groove 3 on the traveling direction R side toward the lateral groove 3 on the traveling direction L side. By forming the communication path 7 at an angle, water that has entered the communication path 7 can be easily discharged.

DESCRIPTION OF SYMBOLS 1 ... Tread part 2 ... Main groove 3 ... Side groove 4 ... Block 5 ... Closed groove
5a ... extension
5b groove bottom 6 concave part 7 communication path 8 first concave part 9 second concave part 10 first die part 11 second die part 12 convex part 13 communication area 14 extension part 15 cylinder Part 16: Projection 17: First closing groove 18: Second closing groove 19: First plate 20: Second plate 21: First plate 22: Second plate 23: Third plate Form 24: Fourth plate-shaped body

Claims (4)

A tread portion, a pneumatic tire having a plurality of main grooves extending in the tire circumferential direction, a plurality of blocks formed by a plurality of lateral grooves extending in the tire width direction,
Said block, without the main groove and said lateral groove opening, a closing groove extending from the top surface to the tire inner diameter direction, respectively formed on the side surface of said block constituting the lateral groove, and a recess communicating with the closed grooves With
Said closure groove and are communicating passage communicating formation between the lateral grooves on both sides of the block by the said recess,
The pneumatic tire according to claim 1, wherein the closing groove has an expanded portion whose cross-sectional area gradually increases from a front side in a traveling direction in a tire circumferential direction to a rear side in a traveling direction . Of the recess, the opening area of the side, the pneumatic tire according to claim 1, wherein greater than the opening area of the communicating portion between the closed grooves constituting the lateral grooves. The groove bottom of the closure grooves, air according to claim 1 or 2, characterized in that inclined from the lateral grooves in the traveling direction front side so as to gradually deeper toward the transverse groove in the traveling direction rear side Containing tires. A tread portion, a plurality of main grooves, the pneumatic tire manufacturing method having a plurality of blocks formed by a plurality of lateral grooves extending in the tire width direction and extending in the tire circumferential direction,
A first mold element to form a closed grooves having an extended portion cross-sectional area toward the traveling direction rear side from the traveling direction front side in the tire circumferential direction in the block is gradually increased, the lateral grooves and recesses on the sides of the block And a second mold part forming
After vulcanization, the after the first mold part was separated from the closed grooves, the pneumatic tire manufacturing method, characterized by disengaging the second mold part from said lateral grooves.

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