JP2012171606A - Pneumatic tire for construction vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for a construction vehicle with excellent wear resistance even when used for any of a driving wheel and a steering wheel.SOLUTION: Zigzag thin grooves 21, lateral thin grooves 32, and width direction thin grooves 22 are arranged in a tread part 10, thereby forming two block rows 24a, 24b in which a plurality of block land parts 23a, 23b in a polygon shape with five sides or more are juxtaposed along a tire circumferential direction. The lateral thin grooves 32a, 32b are arranged within the 1/2-3/4 positional range of a distance from a tire equator to a tread end, and extended in the same direction toward the respective tread ends from the tire equator E side at prescribed inclination angles δ, δrelative to the tire circumferential direction C.

Description

  The present invention relates to a pneumatic tire, in particular, a pneumatic tire for a construction vehicle used for a dump truck or the like mainly used at a construction site or a mine, particularly when used for either a driving wheel or a steering wheel. Also, high wear resistance can be realized.

  As a conventional pneumatic tire for construction vehicles, a pneumatic tire in which a plurality of lug grooves located on both sides of the tread in the tire width direction is generally used. In this pneumatic tire for construction vehicles, in order to improve the wear life of the tire, it is common to increase the tread volume by increasing the tread gauge or decreasing the groove area.

  However, when the wear resistance is improved by using the above-described means, there is a tendency that the heat generation of the tread portion is deteriorated, that is, the temperature of the tread portion is increased, particularly during tire rolling. Such a temperature rise in the tread portion is not preferable because it causes a failure such as heat separation in the tread portion.

  As a countermeasure for this, for example, in Patent Document 1, by using a tread having a predetermined narrow groove in the width direction, the wind flowing in the tread groove is efficiently sent into the groove in the width direction, and the tire center portion is air-cooled. Thus, construction vehicle tires that suppress exothermic deterioration are cited. Further, in Patent Document 2, by forming a predetermined lateral sub-groove in each block land portion that forms the shoulder region of the tread, when the stepping end is kicked off from the road surface, the stepping end is quickly removed from the road surface. There has been disclosed a pneumatic tire that comes apart and reduces uneven wear at the tread edge without significantly reducing land rigidity.

  Also, in construction vehicles used in mines, new tires are temporarily used as front wheels in order to reduce the risk of puncture and improve the wear life of tires by achieving uniform wear on the front and rear wheels. After wearing and using for a certain period of time, it is usually used as a rear wheel. Therefore, when used as a steered wheel as well as when used as a drive wheel, it has been necessary to increase resistance to wear caused by side force input during turning.

JP 2007-191093 A JP 2007-83822 A

  An object of the present invention is to provide a pneumatic tire for a construction vehicle having excellent wear resistance regardless of whether it is used for a drive wheel or a steering wheel by optimizing a tread pattern. is there.

The present inventor is a pneumatic tire for construction vehicles having a plurality of lug grooves in the lateral region when the tread is divided into a central region and both lateral regions located on both sides in the tire width direction of the central region. The study was repeated to solve the above problems.
And, by arranging lug grooves, zigzag narrow grooves, side narrow grooves and width direction narrow grooves in the tread portion, a plurality of pentagonal polygonal block land portions are juxtaposed along the tire circumferential direction. A plurality of quadrangular side block land portions are juxtaposed along the tire circumferential direction by forming two polygonal block rows and arranging lug grooves and circumferential narrow grooves. By forming the side block row of rows, the polygon block land stepped in first pulls the opposing polygon block across the zigzag narrow groove when running as a driving wheel for dump trucks etc. Since the pulled-in polygonal block is in a state of being deformed before it is stepped on, a shearing force is generated between the road surface and the drawn-in polygonal block from the moment when the stepped-on, and the driving performance is improved. Kicking out Shearing force is reduced when the wear resistance when used as the drive wheel can be improved.

  Further, the inventor of the present invention is that the wear of the steered wheel (front wheel) receives input from the side force during steering, and the tread surface deformed to the center side when stepped on returns to the shoulder side (outer in the tire width direction) when kicking It was noticed that slipping was caused, especially in the position range from the tire equator to 3/4 of the distance from the tread edge. As a result of further earnest research, by providing side narrow grooves extending in the same direction from the tire equator side to the respective tread ends at a predetermined inclination angle with respect to the tire circumferential direction, Each polygonal block land part deforms to the shoulder side and returns to its original shape when kicked (returns to the center side), so it is possible to cancel the movement of the shoulder side when kicking, which causes wear. It has been found that the wear resistance can be improved when used as an adhesive.

The present invention has been made based on such findings, and the gist thereof is as follows.
(1) In a pneumatic tire for a construction vehicle having a plurality of lug grooves that are divided into a central region and both side regions located on both sides of the central region in the tire width direction and having a plurality of lug grooves that are open at the end of the tread, The first inclined groove portion extending at a predetermined inclination angle with respect to the tire circumferential direction and the second inclined groove portion extending at an angle opposite to the tire circumferential direction are alternately connected. A zigzag narrow groove extending continuously in a zigzag shape along the tire circumferential direction is provided, and the position range from 1/2 to 3/4 of the distance from the tire equator to the tread edge is defined with respect to the tire circumferential direction. Side narrow grooves extending in the same direction from the tire equator side toward the respective tread ends at a predetermined inclination angle are provided, and the inner side in the tire width direction of the lug groove is a first inclined groove portion and a second inclined groove portion. In the width direction of the tire A widthwise narrow groove is provided between the inner side in the tire width direction of the lug groove and the closer connecting part, and the lug groove, zigzag narrow groove, side narrower are formed in the tread portion. By arranging the groove and the width direction narrow groove, a plurality of pentagonal or more polygonal block land portions form two rows of polygonal block rows juxtaposed along the tire circumferential direction, and the lug groove and By arranging the circumferential narrow grooves, a plurality of quadrangular side block land portions form two side block rows juxtaposed along the tire circumferential direction. Pneumatic tire for construction vehicles.

(2) The pneumatic tire for a construction vehicle according to (1), wherein each of the side narrow grooves has an inclination angle with respect to a tire circumferential direction in a range of 0 ° to 30 ° or less.

(3) The pneumatic tire for a construction vehicle according to (1), wherein the lug grooves positioned in the both side regions are inclined in a range of 50 to 80 ° with respect to the tire circumferential direction.

(4) The pneumatic tire for a construction vehicle according to (3), wherein the lug grooves have the same extending direction from the equator side toward the tread end.

(5) The pneumatic tire for a construction vehicle according to (1), wherein the amplitude of the extending shape of the zigzag narrow groove is 5 to 30% of the tread width.

(6) The pneumatic tire for a construction vehicle according to (1), wherein a groove width of the zigzag narrow groove is 3 to 8% of an arrangement pitch of the block land portion.

(7) The first inclined groove portion extends at an angle of 20 to 50 ° with respect to the tire circumferential direction, and the second inclined groove portion extends at an angle of −20 to −50 ° with respect to the tire circumferential direction. The pneumatic tire for construction vehicles according to (1), characterized in that it is characterized in that

(8) The pneumatic tire for a construction vehicle according to (1), wherein the groove depth of the zigzag narrow groove is 70% or more of the groove depth of the lug groove.

(9) The construction vehicle pneumatic tire according to (1), wherein the pneumatic tire for a construction vehicle is mounted such that the side groove contacts a ground from an end portion on the tire equator side when traveling. Enter tire.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where it is a case where it uses for any of a drive wheel and a steering wheel, the pneumatic tire for construction vehicles which has the outstanding abrasion resistance can be provided.

It is the figure which showed typically a part of tread about one Embodiment of the pneumatic tire for construction vehicles of this invention. It is the figure which showed typically a part of tread about other embodiment of the pneumatic tire for construction vehicles of this invention. It is the figure which showed typically a part of tread of the conventional pneumatic tire for construction vehicles. It is the figure which showed typically a part of tread of the conventional pneumatic tire for construction vehicles. It is the figure which showed typically a part of tread of the pneumatic tire for construction vehicles used as a reference example.

Hereinafter, the configuration of the present invention and the reasons for limitation will be described with reference to FIGS.
FIG. 1 is a diagram schematically showing a part of a tread for an embodiment of a pneumatic tire for construction vehicles of the present invention, and FIG. 2 is another embodiment of the pneumatic tire for construction vehicles of the present invention. It is the figure which showed a part of tread typically about the form, and FIG.3 and FIG.4 is the figure which showed a part of tread of the conventional pneumatic tire for construction vehicles.
1 to 4, the direction of the arrow C in the figure is the tire circumferential direction, the direction of the arrow W is the tire width direction, and the arrow R is the rotation direction.

  As shown in FIG. 1, the pneumatic tire for construction vehicles of the present invention divides the tread 10 into a central area 20 and both side areas 30 located on both sides of the central area 20 in the tire width direction, and opens at the tread end. It is a pneumatic tire for construction vehicles having a plurality of lug grooves 31a, b. Here, the central area 20 refers to an area of 75% or less from the tire equator E to the tread edge, and the side area 30 refers to an area other than the central area 20 of the tread. Further, as shown in FIG. 1, the lug grooves 31a and 31b extend inward in the width direction from the position of 3/4 of the distance from the tire equator E to the tread end, and one side of the side wall is a straight line. The other side is bent (in the present invention, the inner portion in the tire width direction from the bending point is the inner portion in the width direction) and has a tapered shape.

In the present invention, as shown in FIG. 1, in the central region 20, a first inclined groove portion 21a extending at a predetermined inclination angle with respect to the tire circumferential direction, and the first inclined groove portion 21a are arranged in the tire circumferential direction. In contrast, the second inclined groove portions 21b extending at opposite angles are alternately connected to each other, and one zigzag narrow groove 21 continuously extending in a zigzag shape along the tire circumferential direction is provided. In a position range of 1/2 to 3/4 of the distance to the end, at a predetermined inclination angle δ ₁ , δ ₂ with respect to the tire circumferential direction C, in the same direction from the tire equator E side toward each tread end Extending lateral narrow grooves 32a and 32b are provided, and the inner side portions 31a 'and b' of the lug groove 31 are connected to the closer of the connecting portions 21c of the first inclined groove portion and the second inclined groove portion. part _21c 2, _{c 1} and located in the positional relationship facing the tire width direction And wherein the lug grooves 31a, the tire width direction inner side portion of b 31a ', and b', between the connecting portion _21c 2, _{c 1} towards the close, provided the width-direction narrow grooves 22 extending in communication, a tread portion 10 is provided with lug grooves 31a, b, zigzag narrow grooves 21, side narrow grooves 32a, b, and width direction narrow grooves 22, so that a plurality of pentagonal or more polygonal block land portions 23a, 23b are formed. Two block rows 24a and 24b juxtaposed along the tire circumferential direction are formed.
The inclination angles δ ₁ and δ ₂ of the side narrow grooves 32a and b are the angle δ ₁ formed by the straight line connecting the groove width centers of the side narrow grooves 32a and 32b and the tire circumferential direction C, It refers to δ _2.

  By providing the above configuration, the polygon block rows 24a and 24b of the present invention have the tire equator plane E at the tip of each polygon block 23a with the zigzag narrow groove 21 extending zigzag in the tire circumferential direction C. Adjacent to the opposing polygonal block 23b. Accordingly, when traveling as a driving wheel for a dump truck or the like, the polygon block land portion that has been stepped on first (in FIG. 1, the polygonal block land portion 23a that is shaded) has the zigzag narrow groove 21. A part of the polygonal block land part 23b (in FIG. 1, the hatched part of the polygonal block land part 23b) is pulled in, and the part of the drawn polygonal block land part 23b is deformed before it is stepped on. Therefore, a shear force is generated between the polygonal block land portion 23b drawn from the road surface from the moment when the polygonal block land portion 23b is stepped on, and traction can be improved. As a result, by improving the traction, it is possible to reduce the shearing force at the time of kicking out the tire, which is a main cause of wear, so that the wear resistance when used as a drive wheel is improved.

Furthermore, in the position range of 1/2 to 3/4 of the distance from the tire equator to the tread edge, the lug grooves 31a and 31b pass through the tire width direction inner side portions 31a 'and b', and the tire circumferential direction C By installing the side narrow grooves 32a and 32b extending in the same direction at predetermined inclination angles δ ₁ and δ ₂ , the side narrow grooves 32a and 32b are mounted on the construction vehicle so as to be grounded from the center side. When the tire is stepped on, each of the polygonal block land portions 23a, 23b (particularly, the portion where the side narrow grooves 32a, b are disposed) is deformed to the shoulder side (the tire width direction W outside), As a result of the movement returning to the original shape (returning to the center side) when kicking out, the movement of the tread deformed to the center side causing wear to return to the shoulder side when kicking out can be negated. Therefore, the pneumatic tire for construction vehicles of the present invention has excellent wear resistance even when used as a steering wheel.

  Here, the side narrow grooves 32a and 32b are provided in a position range of 1/2 to 3/4 of the distance from the tire equator E to the tread end when the tread deformed to the center side kicks out on the shoulder side. This is because the influence of wear resulting from the slipping back to the maximum is the largest in the range from the tire equator E to the 3/4 position from the tread edge. When the side narrow grooves 32a and 32b are provided in other places, sufficient wear resistance cannot be realized when used as steering wheels.

  In the conventional tread 100, as shown in FIG. 3, the polygonal block land portion 230 is provided with the linear zigzag narrow groove 210 along the tire circumferential direction C interposed therebetween. Thus, there is no improvement in traction due to the shearing force between the drawn polygonal block and the road surface, and it is considered that the wear resistance cannot be sufficiently improved. Further, since the side narrow grooves 320 are not inclined with respect to the tire circumferential direction C and are parallel to each other, the wear resistance when used as a steered wheel cannot be improved.

  Further, as shown in FIG. 4, even in the tread 100 in which the zigzag grooves 21 are arranged along the tire circumferential direction C, the side narrow grooves 320 are not inclined with respect to the tire circumferential direction C. Because it is parallel, when used as a steered wheel, the tread surface deformed to the center side that causes wear cannot cancel the movement back to the shoulder side when kicking out, and exhibits sufficient wear resistance Can not.

Further, as shown in FIG. 1, the extending directions of the side narrow grooves 32a, b are the same from the tire equator side to the respective tread ends (in FIG. 1, both are directed upward). .) Furthermore, in order to more effectively demonstrate the effect of the present invention (the effect of canceling the movement of the tread surface deformed toward the center side that causes wear back to the shoulder side when kicking out), the side narrow grooves 32a, b The inclination angles δ ₁ and δ ₂ are preferably in the range of more than 0 ° and not more than 30 °.

  The pneumatic tire of the present invention travels in the rotational direction R during traveling (in FIG. 1, the lower side is the stepping side (ground)) from the viewpoint of obtaining the above-mentioned wear resistance when used as a steering wheel. ), The side narrow grooves 32a and 32b and the lug grooves 31a and 31b need to be mounted on the vehicle so as to be grounded from the end on the tire equator E side.

  Further, the side narrow grooves 32a, b are assembled on the regular rim of the TRA, and after filling the regular internal pressure of the TRA, when the tire is grounded in a state where the normal load (100%) of the TRA is applied, b is not closed. This is to ensure high heat resistance.

The lug grooves 31a and 31b located in the both side regions 30 are preferably inclined with respect to the tire circumferential direction C in the range of 50 to 80 °. This is because when the inclination angles γ ₁ and γ ₂ are less than 50 °, the shape of the lug grooves 31a and 31b becomes elongated, so that the lug rigidity is deteriorated and the wear resistance may be lowered. _1, if the gamma ₂ is less than 100 °, the deformation of the tire width direction outside the outer during the depression is reduced, the motion to return to the shoulder side can be canceled sufficiently when kicking it tread deformed to the center side This is because the effect of wear resistance may not be sufficiently exhibited.
The inclination angles γ ₁ and γ ₂ of the lug grooves 31a and 31b are defined by the straight line connecting the center of the groove width of the lug grooves 31a and b at the position of 3/4 from the tire equator E to the tread end, and the tire. This means the angles δ ₁ and δ ₂ formed with the circumferential direction C.

  Furthermore, as shown in FIG. 2, the lug grooves 31a and 31b preferably have the same extending direction from the tire equator E side to the tread end. This is because the above-described effect of canceling the movement of the tread surface deformed toward the center side that causes wear back to the shoulder side when kicking out can be effectively exhibited.

  In addition, the zigzag narrow groove 21 extends continuously in a zigzag shape along the tire circumferential direction by alternately connecting the first inclined groove portion 21a and the second inclined groove portion 21b to the central region 20. It is a groove. Other configurations are not particularly limited, but the groove depth is preferably 70% or more of the groove depth of the lug groove. If the groove depth of the zigzag narrow groove 21 is less than 70%, the tread may be worn out at the end of use of the tire, and the zigzag narrow groove 21 may disappear, and the effects of the present invention may not be sufficiently exerted. This is because the air cooling effect is lost, and as a result, the tread may generate heat and cause a failure.

  As shown in FIG. 1, the amplitude T of the extending shape of the zigzag narrow groove 21 is preferably 5 to 30% of the tread width TW. When the amplitude T is less than 5%, the force for drawing a part of the polygonal block 23 becomes small, the traction cannot be improved sufficiently, and the wear resistance may not be improved sufficiently. On the other hand, if the amplitude T exceeds 30%, the block rigidity of the center portion is lowered and the wearability cannot be improved.

Further, the first inclined groove portion 21a preferably extends at an angle α of 20 to 50 ° with respect to the tire circumferential direction. When the angle α is less than 20 °, the force for drawing a part of the polygonal block 23 becomes small, the traction cannot be sufficiently improved, and the wear resistance may not be sufficiently improved. If the angle exceeds 50 °, the block rigidity of the center portion decreases, and the wear resistance cannot be improved. For the same reason, the second inclined groove 21b preferably extends at an angle β of −20 to −50 ° with respect to the tire circumferential direction.
In addition, as shown in FIG. 1, the inclination angle of the inclined portions 21a and 21b in the present invention is an angle formed by a straight line connecting the groove width center at the connection point 21c of the zigzag groove 21 and the tire circumferential direction. α and β, where the installation surface is down, the clockwise angle with respect to the tire circumferential direction C is a positive angle, and the counterclockwise angle is a negative angle.

  Furthermore, as shown in FIG. 1, the groove width U of the zigzag narrow groove 21 is preferably 3 to 8% of the arrangement pitch A of the block land portion 23. This is because, when the groove width U of the zigzag narrow groove 21 is less than 3% of the arrangement pitch, the groove width is too narrow, so that a heat dissipation effect cannot be obtained and heat generation may be deteriorated. If the groove width U exceeds 8%, the force for drawing a part of the polygonal block 23 becomes small, the traction cannot be improved sufficiently, and the wear resistance may not be improved sufficiently. Because there is.

  The zigzag narrow groove 21 is assembled to a regular rim of the TRA, and after filling the regular internal pressure of the TRA, the groove 21 is closed when the tire contacts the ground while applying a regular load (100%) of the TRA. Yes. This is to ensure a desired block rigidity.

In addition, the width direction narrow groove 22 is a groove that extends in communication between the tire width direction inner side portion 31 ′ of the lug groove 31 and the connecting portion 21 c ₂ of the closer zigzag narrow groove 21. Other configurations are not particularly limited.
However, like the zigzag narrow groove 21, the width direction narrow groove 22 is preferably 3 to 8% of the arrangement pitch A of the block land portions 23. When the groove width of the width direction narrow groove 22 is less than 3% of the arrangement pitch, since the groove width is too narrow, a heat dissipation effect cannot be obtained, and heat generation may be deteriorated. If the groove width exceeds 8%, the force for drawing a part of the polygonal block 23 becomes small, the traction cannot be improved sufficiently, and the wear resistance may not be improved sufficiently. Because there is.

  Furthermore, as shown in FIG. 1, it is preferable that the extending direction of the width direction narrow groove 22 is the same as the extending direction of the lug grooves 31a and 31b. As with the lateral block land portions 33a and 33b, the lateral block land portions 23a and 23b are moved toward the shoulder side when the tire is depressed, due to the inclination of the width direction narrow groove 22. Tire width direction W outside), and when it kicks out, it returns to its original shape (returns to the center side), which causes wear when used as a steering wheel. It is possible to cancel the movement of the tread deformed to the side back to the shoulder when kicking out. As a result, the pneumatic tire for construction vehicles of the present invention can effectively suppress wear even when used as a steering wheel.

  The narrow groove 22 in the width direction is closed when the tire is grounded in a state where the TRA is loaded on the normal rim of the TRA, and after the normal internal pressure of the TRA is charged and the normal load (100%) of the TRA is applied. ing. This is to ensure a desired block rigidity.

In the present invention, the polygonal block land portion 23 formed by the zigzag narrow groove 21, the side narrow groove 32, the lug groove 31 and the width direction narrow groove 22 is formed in the tire circumferential direction as shown in FIG. Two block rows 24a and 24b are formed by being juxtaposed along c.

Further, the polygonal block land portion 23 is not particularly limited as long as it is a pentagon or more, and depending on the shape of the inner side portion 31 ′ of the lug groove 31 in the tire width direction, for example, as shown in FIG. It can also be a polygonal block, or can be a heptagonal or pentagonal polygonal block land portion 23.
Whether it is pentagonal, hexagonal or heptagonal, to improve the traction, reduce the shear force when kicking the tire, which is the main factor of wear, and improve the wear resistance. Can do.

  The above description is merely an example of the embodiment of the present invention, and various modifications can be made within the scope of the claims.

Example 1
As an example, the tire size is 46/90 R 57, and as shown in FIG. 1, a plurality of lug grooves 31 a, b (extension direction and inclination angle γ ₁ , γ ₂ is shown in Table 1.), and in the central region 20, a first inclined groove portion 21a extending at a predetermined inclination angle α (Table 1) with respect to the tire circumferential direction, and the first inclined groove portion 21a Is alternately connected to the second inclined groove portions 21b extending at an angle β opposite to the tire circumferential direction (Table 1), and continuously extends in a zigzag shape along the tire circumferential direction. A narrow groove 21 is provided and extends at a predetermined inclination angle δ ₁ , δ ₂ (Table 1) with respect to the tire circumferential direction in a position range of 1/2 to 3/4 of the distance from the tire equator E to the tread edge. The narrow grooves 32a and 32b are provided, and the inner side portions 31a 'and b' of the lug groove 31 in the tire width direction are the first inclined groove portion and There the connecting portion 21c _2, c ₁ and the tire width direction to the opposite arrangement of the closer of the connecting portion 21c of the inclined groove portion and the tire width direction inner side portion of the lug groove 31a ', and b', who the closer between the connecting portion _21c 2, _{c 1} of the width-direction narrow grooves 22 extending in communication provided in the tread portion 10, the lug grooves 31a, b, zigzag narrow groove 21, the lateral narrow groove 32 and the width direction fine By providing the groove 22, air that forms two rows of block rows 24a, b in which a plurality of polygonal block land portions 23a, b (hexagonal in FIG. 1) are juxtaposed along the tire circumferential direction. An entering tire was produced as a sample.
The groove depth (mm) of the lug grooves 31a, b of the produced pneumatic tire, the angle (°) of the lug grooves 31a, b with respect to the tire circumferential direction C, the groove depth (mm) of the zigzag narrow groove 21, and the lug groove The groove depth (%) of the zigzag narrow groove 21 with respect to the groove depths 31a and 31b, the ratio (%) of the amplitude T of the extending shape of the zigzag to the tread width TW, the first inclined groove portion 21a with respect to the tire circumferential direction C, the first Table 1 shows the angle (°) of the two inclined groove portions 21a, the position of the side narrow grooves 32a, 32b in the tire width direction and the angle (°) of the side narrow grooves 32a, b with respect to the tire circumferential direction C.

(Example 2)
As Example 2, as shown in FIG. 2, samples were prepared under the same conditions as in Example 1 except that the inclination angles δ ₁ and δ _{2 of the} side narrow grooves 32a and b with respect to the tire circumferential direction C were different. Produced. In FIG. 2, the side narrow grooves 32 a and 32 b are not in the position range of 1/2 to 3/4 of the distance from the tire equator E to the tread end, but this is different from the first embodiment. This is because the inclination angles δ ₁ and δ ₂ of the side narrow grooves 32a and 32b are increased for the sake of facilitating the actual operation. In practice, the distance from the tire equator E to the tread end is 1/2 to 3/4. It is located in the range.
The groove depth (mm) of the lug grooves 31a, b of the produced pneumatic tire, the angle (°) of the lug grooves 31a, b with respect to the tire circumferential direction C, the groove depth (mm) of the zigzag narrow groove 21, and the lug groove The groove depth (%) of the zigzag narrow groove 21 with respect to the groove depths 31a and 31b, the ratio (%) of the amplitude T of the extending shape of the zigzag to the tread width TW, the first inclined groove portion 21a with respect to the tire circumferential direction C, the first Table 1 shows the angle (°) of the two inclined groove portions 21a, the position of the side narrow grooves 32a, 32b in the tire width direction and the angle (°) of the side narrow grooves 32a, b with respect to the tire circumferential direction C.

(Comparative Example 1)
As shown in FIG. 3, the comparative example 1 is not zigzag but includes a conventional tread 100 in which a polygonal block land portion 230 is provided with a central narrow groove 210 extending linearly along the tire circumferential direction. A tire having the same conditions as in Example 1 was used as a sample except for the above.
In the produced pneumatic tire, the groove depth (mm) of the lug groove 31, the angle (°) of the lug grooves 31 a and b with respect to the tire circumferential direction C, the groove depth (mm) of the zigzag fine groove 21, The groove depth (%) of the zigzag narrow groove 21 with respect to the groove depth, the amplitude (%) of the extending shape of the zigzag with respect to the tread width, the tire width direction position of the side narrow grooves 32a, b with respect to the tire circumferential direction C, and the tire circumference Table 1 shows the angle (°) of the side narrow grooves 32a and 32b with respect to the direction C.

(Comparative Example 2)
In Comparative Example 2, as shown in FIG. 4, the extending directions of the lug grooves 31 located in the both side regions 30 with respect to the tire circumferential direction C are different, and the side narrow grooves 32 a and 32 b are in the tire circumferential direction. A sample was produced under the same conditions as in Example 1 except that it was parallel to C (inclination angle 0 ° with respect to the tire circumferential direction C).
The groove depth (mm) of the lug grooves 31a, b of the produced pneumatic tire, the angle (°) of the lug grooves 31a, b with respect to the tire circumferential direction C, the groove depth (mm) of the zigzag narrow groove 21, and the lug groove The groove depth (%) of the zigzag narrow groove 21 with respect to the groove depths 31a and 31b, the ratio (%) of the amplitude T of the extending shape of the zigzag to the tread width TW, the first inclined groove portion 21a with respect to the tire circumferential direction C, the first Table 1 shows the angle (°) of the two inclined groove portions 21a, the position of the side narrow grooves 32a, 32b in the tire width direction and the angle (°) of the side narrow grooves 32a, b with respect to the tire circumferential direction C.

(Comparative Example 3)
Further, as shown in FIG. 5, Comparative Example 3 is similar to Example 1 except that the side narrow grooves 32a and 32b are parallel to the tire circumferential direction C (inclination angle 0 ° with respect to the tire circumferential direction C). Samples were prepared under the same conditions.
The groove depth (mm) of the lug grooves 31a, b of the produced pneumatic tire, the angle (°) of the lug grooves 31a, b with respect to the tire circumferential direction C, the groove depth (mm) of the zigzag narrow groove 21, and the lug groove The groove depth (%) of the zigzag narrow groove 21 with respect to the groove depths 31a and 31b, the ratio (%) of the amplitude T of the extending shape of the zigzag to the tread width TW, the first inclined groove portion 21a with respect to the tire circumferential direction C, the first Table 1 shows the angle (°) of the two inclined groove portions 21a, the position of the side narrow grooves 32a, 32b in the tire width direction and the angle (°) of the side narrow grooves 32a, b with respect to the tire circumferential direction C.

(1. Wear resistance when wearing front wheels)
The pneumatic tires of Examples 1 and 2 and Comparative Examples 1 to 3 are assembled on the regular rim of TRA, and after filling the regular internal pressure of TRA, the front wheel of the vehicle is set to the rotational direction R shown in FIGS. After mounting as a (steering wheel) and running in the market, measuring the groove depth (mm) at a predetermined position of the tread (25% outside the center with respect to the tread width) Evaluation was performed. The results are shown in Table 2.
The evaluation result is represented by a relative ratio (%) when the wear resistance of the tire of Comparative Example 1 is 100%, and the larger the numerical value (%), the better the result.

(2. Wear resistance when the rear wheel is mounted)
The pneumatic tires of Examples 1 and 2 and Comparative Examples 1 to 3 were assembled on a regular rim of TRA, and after the regular internal pressure of TRA was filled, the vehicle was mounted on the vehicle as a rear wheel (drive wheel) and traveled in the market. Then, the wear resistance was evaluated by measuring the groove depth (mm) at a predetermined position of the tread (25% outside the center with respect to the tread width). The results are shown in Table 2.
The evaluation result is represented by a relative ratio (%) when the wear resistance of the tire of Comparative Example 1 is 100%, and the larger the numerical value (%), the better the result.

(3. Total wear resistance)
The average value of the evaluation results of 1 and 2 was evaluated as an index value of total wear resistance.
The evaluation result is represented by a relative ratio (%) when the wear resistance of the tire of Comparative Example 1 is 100%, and the larger the numerical value (%), the better the result.

  From the results of Table 2, both Examples 1 and 2, which are pneumatic tires according to the present invention, have higher wear resistance when used for front wheels and rear wheels than Comparative Examples 1, 2 and 3. I found it expensive. In particular, in Example 1 in which the inclination angle of the side narrow groove was optimized, it was found that the wear resistance when used for the front wheel and the rear wheel was greatly improved.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the pneumatic tire for construction vehicles which has the outstanding abrasion resistance, even when it is a case where it is a case where it is used for any of a driving wheel and a steering wheel.

10, 100 Tread 20, 200 Central region 21, 210 Zigzag narrow groove 22, 220 Width direction narrow groove 23, 230 Polygon block land portion 24, 240 Polygon block row 30, 300 Side region 31, 310 Lug groove 32, 320 Side narrow groove 33, 330 Side block land 34, 340 Side block row

Claims (9)

In the pneumatic tire for construction vehicles, which divides the tread into a central area and both side areas located on both sides in the tire width direction of the central area, and has a plurality of lug grooves opened at the tread end,
In the center region, first inclined groove portions extending at a predetermined inclination angle with respect to the tire circumferential direction and second inclined groove portions extending at an angle opposite to the tire circumferential direction are alternately arranged. To provide a single zigzag narrow groove extending continuously in a zigzag shape along the tire circumferential direction,
Extends in the same direction from the tire equator side to each tread edge at a predetermined inclination angle with respect to the tire circumferential direction within a position range of 1/2 to 3/4 of the distance from the tire equator to the tread edge. Side grooves are provided,
The inner side portion of the lug groove in the tire width direction is in an arrangement relationship facing the closer connecting portion of the connecting portions of the first inclined groove portion and the second inclined groove portion in the tire width direction, and the tire width direction of the lug groove A width direction narrow groove is provided between the inner portion and the closer connecting portion,
By arranging lug grooves, zigzag narrow grooves, side narrow grooves, and width direction narrow grooves in the tread portion, a plurality of pentagonal or more polygonal block land portions are juxtaposed along the tire circumferential direction. By forming two polygonal block rows and arranging lug grooves and circumferential narrow grooves, two rows of quadrangular or more side block land portions are juxtaposed along the tire circumferential direction. A pneumatic tire for construction vehicles, characterized by forming a side block row.   2. The pneumatic tire for construction vehicles according to claim 1, wherein each of the lateral narrow grooves has a range in which the inclination angle with respect to the tire circumferential direction is greater than 0 ° and less than or equal to 30 °.   2. The pneumatic tire for construction vehicles according to claim 1, wherein the lug grooves located in the both side regions are inclined in a range of 50 to 80 ° with respect to the tire circumferential direction.   The pneumatic tire for a construction vehicle according to claim 3, wherein the lug grooves have the same extending direction from the equator side to the tread end.   The pneumatic tire for a construction vehicle according to claim 1, wherein the amplitude of the extending shape of the zigzag narrow groove is 5 to 30% of the tread width.   The pneumatic tire for a construction vehicle according to claim 1, wherein a groove width of the zigzag narrow groove is 3 to 8% of an arrangement pitch of the block land portion.   The first inclined groove portion extends at an angle of 20 to 50 ° with respect to the tire circumferential direction, and the second inclined groove portion extends at an angle of −20 to −50 ° with respect to the tire circumferential direction. The pneumatic tire for construction vehicles according to claim 1.   The pneumatic tire for a construction vehicle according to claim 1, wherein the groove depth of the zigzag narrow groove is 70% or more of the groove depth of the lug groove.   The pneumatic tire for a construction vehicle according to claim 1, wherein the pneumatic tire for a construction vehicle is mounted so that the side groove comes into contact with an end on the tire equator side when traveling.

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