JP5251274B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire. More specifically, the present invention relates to a pneumatic tire that can improve the discharge of foreign matters such as stones entering a tread groove and can exhibit this discharge over a long period of time.

  The tread groove formed in the tread portion of the pneumatic tire may bite foreign substances such as stones, and various tires have been proposed in which a protrusion that prevents so-called stone biting is provided at the groove bottom of the tread groove (for example, , See Patent Document 1). In the tire described in Patent Document 1, a large number of protrusions are arranged with gaps in the length direction of the tread groove, and each protrusion is formed independently without being connected to the groove wall of the tread groove.

  For this reason, foreign matter is easily caught between the protrusion and the groove wall of the tread groove, and it is difficult to ensure the rigidity of the protrusion, so that the entire protrusion is easily deformed excessively by the foreign matter that has entered the tread groove. Therefore, this protrusion cannot sufficiently prevent foreign matter from entering the tread groove, and if the foreign object is caught, the protrusion is damaged and the stone biting prevention function cannot be exhibited. was there.

If a foreign object such as a stone is continuously used while being bitten in the groove, a small damage may be enlarged and the tire may not be used. Tires mounted on construction vehicles such as dump trucks, wheel loaders, wheeled hydraulic excavators, etc. often run on unpaved road surfaces where there are many foreign objects such as stones. In particular, it was necessary to take high-level measures.
Japanese Patent Laid-Open No. 3-67706

  An object of the present invention is to provide a pneumatic tire that can improve the discharge of foreign matters such as stones entering a tread groove and can exhibit this discharge over a long period of time.

In order to achieve the above object, in the pneumatic tire of the present invention, a plurality of land portions are partitioned by a plurality of tread grooves formed in the tread portion, and a protruding portion having a height lower than that of the land portion is formed on the bottom of the tread groove. In the pneumatic tire provided with the tread groove in the tread groove width direction at the position where the protrusion is provided on the upper surface of the protrusion, and the protrusion is connected to only one of the groove walls of the tread groove. An extending narrow groove is provided , the protrusion is opposed to the tread groove width direction, and is shifted in the tread groove length direction so as to partially overlap each other, and the depth of the narrow groove is determined by the protrusion. The width of the narrow groove is set to 15% or more and 25% or less of the top surface width of the protrusion, and the groove bottom of the narrow groove is formed in an arc shape. At both ends of the tread groove length direction, Characterized in that the formation of the inclined surface inclined in the direction of the tapered upper surface of the projecting portion of the.

Here, for example, the angle formed by the inclined surface and the groove bottom of the tread groove is set to 30 ° or more and 60 ° or less. For example, the height of the protruding portion is set to 15% or more and 25% or less of the height of the land portion. An example of the tread groove provided with the protruding portion is a lug groove.

  According to the present invention, in a pneumatic tire in which a protrusion having a height lower than the land is provided at the groove bottom of the tread groove that divides a plurality of land portions, the protrusion is connected to the groove wall of the tread groove, Since the narrow groove extending in the tread groove width direction at the position where the protrusion is provided is provided on the upper surface of the protrusion, the protrusion can prevent foreign matters such as stones entering the tread groove from entering. Furthermore, when the tread groove bites foreign matter, the protruding portion is pressed by the foreign matter caught by rolling of the tire, and the protruding portion is skillfully centered on the narrow groove formed on the upper surface along with this. Thus, the foreign matter can be discharged to the outside along the length of the tread groove. And since the protrusion part is reinforced by connecting with a groove wall, it is hard to damage and can demonstrate the discharge | emission function of a foreign material over a long period of time.

  Hereinafter, the pneumatic tire of the present invention will be described based on the embodiments shown in the drawings.

  As illustrated in FIG. 1, a plurality of tread grooves 4 formed in a tread portion 2 of a pneumatic tire 1 (hereinafter, referred to as a tire 1) of the present invention are lugs extending in parallel or inclined in the tire width direction. It is a groove. A plurality of blocks 3 are formed by these tread grooves 4, and the upper surface of the block 3 is partitioned as a land portion 3a which is a ground contact surface. Among the plurality of tread grooves 4, a tread groove 4 (A portion and B portion in FIG. 1) in the center in the tire width direction is provided with a protruding portion 5 having a height lower than that of the land portion 3a.

  As shown in FIGS. 2 and 3, the protrusion 5 provided in the portion A of FIG. 1 is connected to only one of the groove walls 4 a and 4 b of the tread groove 4. ing. Since the two projecting portions 5 shown in FIG. 2 have the same specifications, FIG. 3 shows one projecting portion 5 as a representative. Furthermore, on the upper surface of the protruding portion 5, there is one narrow groove 6 extending in the tread groove width direction at the position where the protruding portion 5 is provided. That is, the narrow groove 6 is extended in a direction substantially orthogonal to the extending direction of the tread groove 4. Inclined surfaces 7 are formed at both ends of the protruding portion 5 in the tread groove length direction, and are symmetrical with respect to the narrow groove 6. The height h of the protrusion 5 is set to 15% or more and 25% or less of the height of the land portion 3a (depth of the tread groove 4), for example.

And this protrusion part 5 is shifted and arrange | positioned in the tread groove length direction while facing a tread groove width direction. That is, the pair of projecting portions 5 and 5 are arranged so as to be opposed to the tread groove width direction with a gap g in the tread groove width direction and shifted in the tread groove length direction so as to partially overlap each other. Yes.

Since such a protrusion 5 is provided on the groove bottom 4c of the tread groove 4, if a foreign substance S such as a stone tries to enter the tread groove 4, it can be rebounded and prevented by the rubber protrusion 5. . Depending on the size and shape of the foreign matter S, the tread groove 4 may bite the foreign matter S without being able to be immediately discharged from the tread groove 4 by the protrusion 5.
In such a case, as illustrated in FIG. 4, the protruding portion 5 is pressed by the foreign matter S bitten by rolling of the tire 1, and accordingly, the protruding portion 5 centering on the narrow groove 6. Is deformed. At that time, since the narrow groove 6 is extended in the tread groove width direction, the upper surface of the protruding portion 5 is deformed so as to contract in the tread groove length direction, and the elasticity of the deformed protruding portion 5 causes the foreign matter. A discharging force in the tread groove length direction acts on S.

  As described above, the discharge force acts on the foreign matter S due to the skillful deformation of the protruding portion 5 and is discharged to the outside along the tread groove length direction as illustrated in FIG. Since the protrusion 5 is reinforced by being connected to any one of the groove walls 4a and 4b, it is excessively deformed as compared with the case where the protrusion 5 is formed separately from the groove walls 4a and 4b. There is nothing to do. Further, the deformation of the protrusion 5 mainly occurs around the narrow groove 6, and the root portion of the protrusion 5 (in the vicinity of the groove bottom 4c) is not greatly deformed. Therefore, the protrusion 5 is not easily damaged, and the above-described discharge function of the foreign matter S can be exhibited for a long time.

  In particular, in this embodiment, since the opposing projecting portions 5 are arranged so as to be shifted in the tread groove length direction, the discharging force can act on the foreign matter S in various directions to improve the discharging performance. It has become. The gap g between the protruding portions 5 facing each other is appropriately set in consideration of durability while ensuring the deformation of the protruding portions 5.

The depth d of the narrow groove 6 is set to 40% or more and less than 100% of the height h of the protrusion 5. When the ratio d / h is less than 40%, the deformation amount of the protrusion 5 is small, and the dischargeability of the foreign matter S tends to be insufficient. On the other hand, when the ratio d / h is 100%, the protruding portion 5 is completely divided by the narrow groove 6, and the rigidity is lowered to make it difficult to ensure sufficient durability. The width w of the narrow groove 6 is related to the depth d, but is set to 15% or more and 25% or less of the upper surface width W of the protrusion 5. The number of narrow grooves 6 is not limited to one, but a plurality of narrow grooves 6 may be provided, but one or two is appropriate in consideration of the degree of deformation contribution to the protrusion 5 and durability.

As shown in this embodiment , both end portions of the protruding portion 5 in the tread groove length direction are provided with the inclined surfaces 7 that are inclined in a direction in which the upper surface of the protruding portion 5 is tapered, so that the foreign matter S can be easily discharged. In particular, the foreign object S can be more easily discharged from the tread groove 4 by setting the inclination angle a1 formed by the inclined surface 7 and the groove bottom 4c to 30 ° or more and 60 ° or less.

The protrusion part 5 of a reference form can also provide one independently, without making two oppose as mentioned above. Moreover, although the protrusion part 5 can also be formed so that it may connect with both groove wall 4a, 4b to both tread groove | channels 4, it is preferable to form so that it may connect only with any one groove wall 4a, 4b. . The protrusions 5 connected to both the groove walls 4a and 4b are excessively reinforced by the groove walls 4a and 4b, so that the deformation when the foreign matter S is bitten is reduced and the dischargeability of the foreign matter S is reduced. is there. By connecting the protrusion 5 only to any one of the grooves 4a and 4b, an appropriate reinforcing effect can be obtained, an appropriate amount of deformation can be obtained, and the dischargeability of the foreign matter S above a certain level can be easily secured. Become.

The protrusion part 5 used as the reference form provided in B part of FIG. 1 is illustrated in FIG. 6, FIG. The protruding portion 5 has basically the same specifications as the protruding portion 5 of the previous embodiment, but differs greatly in that it is provided independently without facing in the tread groove width direction. Since this protruding portion 5 is provided at a portion where the three tread grooves 4 intersect, as shown in FIG. 6, if the opposite end face connected to the groove wall 4 a is an inclined surface 7, the foreign matter S It becomes easy to discharge.

In this reference form , since the three end surfaces of the protruding portion 5 are inclined surfaces 7, the bitten foreign matter S is discharged in the tread groove length direction of any of the three intersecting tread grooves 4. Can do. Various other specifications can be made the same as in the previous embodiment.

In the embodiment and the reference embodiment described above, the protrusion 5 is provided on the groove bottom 4c of the tread groove 4 at the center portion in the tire width direction, but the tread groove 4 extending from the center portion in the tire width direction to the end portion in the tire width direction is provided. The various protrusions 5 described above can also be provided. In addition to the lug grooves, the various protrusions 5 described above can be provided on the groove bottom 4c of the tread groove 4 extending in the tire direction.

  The present invention can be applied to various types of pneumatic tires. However, the present invention is applied to heavy vehicles including construction vehicles such as dump trucks, wheel loaders, and wheeled hydraulic excavators and travels on an unpaved road surface. Particularly suitable for pneumatic tires for vehicles.

It is a top view which illustrates a part of tread part of the pneumatic tire of the present invention. It is the A section enlarged view of FIG. It is A1-A1 sectional drawing of FIG. It is explanatory drawing which illustrates the state which has deform | transformed with the foreign material which the protrusion part of FIG. 3 bite. It is explanatory drawing which illustrates the state which discharges the biting foreign material of FIG. It is the B section enlarged view of FIG. It is B1-B1 sectional drawing of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Block 3a Land part 4 Tread groove 4a, 4b Groove wall 4c Groove bottom 5 Protrusion part 6 Fine groove 7 Inclined surface g Clearance S Foreign object

Claims (4)

In a pneumatic tire in which a plurality of land portions are defined by a plurality of tread grooves formed in the tread portion, and a protrusion portion having a height lower than the land portion is provided at the groove bottom of the tread groove, the protrusion portions are tread grooves. with connecting only one of the groove wall of the groove wall of the upper surface of the projecting portion, a narrow groove extending in the tread groove width direction at a position provided with the projecting portion is provided, the protruding portion, the tread grooves The thin grooves are opposed to each other in the width direction, and are shifted in the tread groove length direction so as to partially overlap each other, so that the depth of the narrow groove is 40% or more and less than 100% of the height of the protruding portion. The width of the groove is set to 15% or more and 25% or less of the upper surface width of the protruding portion, the groove bottom of the narrow groove is formed in an arc shape, and the protruding portion is formed at both ends of the tread groove length direction of the protruding portion. Inclined surface that inclines in the direction of tapering the upper surface of A pneumatic tire characterized by forming the. The pneumatic tire according to claim 1 , wherein an angle formed by the inclined surface and a groove bottom of the tread groove is set to 30 ° or more and 60 ° or less . The pneumatic tire according to claim 1 or 2 , wherein a height of the protruding portion is set to 15% or more and 25% or less of a height of the land portion . The pneumatic tire according to claim 1 , wherein the tread groove provided with the protruding portion is a lug groove.

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