JPH11139113A - Pneumatic tire for heavy load - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire for a heavy load provided with point- symmetric lug type patterns for a tread, and excellent in abrasion resistance performance. SOLUTION: In a lug in which a side apart from a tire equatorial line is grounded in advance and a side near to the equatorial line is grounded afterward at the time of rotation (normal rotation) of a tire, a side wall angle αof a treading side is larger than a side wall angle β of a kicking-out side, and the side wall angle α of the treading side is gradually enlarged from the side near to the tire equatorial line EL toward the side apart from the equatorial line EL. In lugs 21, 22 in which sides of near to the equatorial line of the tire are grounded in advance and sides apart from the equatorial line are grounded afterward at the time of rotation of tire (normal rotation), side wall angles βof treading sides are smaller than wall sides angles α of kicking-out sides, and the kicking-out sides angles α are enlarged gradually from the sides near to the equatorial line of the tire toward sides apart from the equatorial line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire, and more particularly to a heavy-duty pneumatic tire provided with a lug-type pattern on a tread and used in trucks, industrial vehicles, construction vehicles, and the like. Things.

[0002]

2. Description of the Related Art In general, a pneumatic tire provided with a lug-type pattern on a tread has excellent driving force and braking force, and particularly excellent traction force on an unpaved road. Therefore, when heavy-duty pneumatic tires used in trucks, industrial vehicles, and construction vehicles are required to have strong driving, braking, and traction on unpaved roads, lug patterns are often adopted. Is done.

In many cases, pneumatic tires for heavy loads such as for trucks, industrial vehicles, and construction vehicles are required to have excellent wear resistance. Also, with heavy duty pneumatic tires for construction vehicles, etc., it is often difficult to specify the direction of rotation (forward rotation) of the tire when mounted on the vehicle, so a point-symmetric lug pattern is provided on the tread. Pneumatic tires are required.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heavy-duty pneumatic tire having a point-symmetric lug pattern on a tread and having excellent wear resistance.

[0005]

In order to achieve the above-mentioned object, a tire according to the present invention extends from a central region of a tread toward one of right and left side regions in a direction inclined in a tire rotation axis direction. One of the left and right lateral grooves opening at the tread end, and forming a pair with the one lateral groove, extending in a direction inclined in the tire rotation axis direction from the central region of the tread toward the other side region. The other lateral groove opening at the tread end is formed in large numbers at intervals in the circumferential direction, so that one lug and the other lug are formed in pairs at right and left intervals in the circumferential direction. (1) the one lateral groove and the other lateral groove are point-symmetric with respect to a point on the equatorial line of the tire, and (2) the one lug or the one lug. Of the other lag, In a lug in which the side farther from the tire equator contacts first and the side closer to the equatorial line contacts later during rotation of the ear (forward rotation), the side wall angle α on the stepping side is larger than the side wall angle β on the kicking side and the stepping on. The side wall angle α gradually increases from the side closer to the tire equator line to the side farther from the equator line, and (3) the one lug or the other lug when the tire rotates (forward rotation) In a lug where the side closer to the equator line contacts first and the side farther from the equator line contacts later, the side wall angle β on the stepping side is smaller than the side wall angle α on the kicking side, and the side wall angle α on the kicking side is the tire equator. A heavy-duty pneumatic tire characterized by gradually increasing in size from the side closer to the line to the side farther from the equator line. In the tire according to the present invention, the side wall angles α and β are 0 degrees or more and 35 degrees or less, and the side wall angles continuously change from the side far from the tire equator to the side close to the equator. Is preferred. In this specification,
The “sidewall angle” of a groove or lug refers to the angle of the groove or lug sidewall with respect to the normal to the tread surface.

[0006] It extends in a direction inclined in the tire rotation axis direction,
A tire according to the present invention comprising a pair of left and right lateral grooves opening at the tread edge, one lateral groove and the other lateral groove being point symmetric with respect to a point on the equator line of the tire,
At the time of ground contact rolling, on either one of the left and right sides of the tire equator line, the side where the lug is farther from the tire equatorial line touches first, the side closer to the equatorial line touches later, and on the other side the lug is closer to the tire equatorial line. Ground first and the side farther away from the equator will ground later.

In a lug in which the side farther from the tire equator is grounded first and the side closer to the equator is grounded later, if the side farther from the tire equatorial line grounds first deforms greatly, the deformation is sequentially grounded. To the side close to
This will increase the deformation of the entire lug. The tire according to the present invention is configured as described above. In particular, in a lug in which the side farther from the tire equator is grounded first and the side closer to the equator is grounded later when the tire is rotating (forward rotation), Since α is larger than the side wall angle β on the kick-out side, deformation at the start of contact with the ground can be suppressed, and the rigidity of the shoulder against the circumferential shear force increases, effectively deforming the entire lug. It is possible to obtain a tire which is suppressed and has excellent wear resistance. The tire according to the present invention is configured as described above. In particular, the side wall angle α on the stepping side gradually increases from the side close to the tire equator line to the side far from the equator line. On the side close to the line, the contribution to suppress the deformation of the lug is small,
This is to increase the wear volume of the rubber.

On the other hand, in the lug on the opposite side where the side closer to the tire equator is grounded first and the side farther from the equator is later grounded, the rigidity near the tire equator is high, so that the deformation is sequentially grounded as described above. It is less likely to be transmitted in the direction in which it is performed. However, on the side farther from the equator line, a braking input is acting on the ground contact surface due to a difference in diameter, and a displacement caused by this input at the time of kicking out may cause wear. This shift displacement acts in the direction opposite to the tire rotation direction. The tire according to the present invention is configured as described above. In particular, in a lug in which the side closer to the tire equator is grounded first and the side farther from the equator is grounded later when the tire is rotating (forward rotation), Since β is smaller than the side wall angle α on the kicking-out side, the rigidity on the kicking-out side is increased, and the wear due to the displacement at the time of kicking is effectively suppressed. The tire according to the present invention has the above-described configuration. Particularly, in a lug in which the side closer to the tire equator is grounded first and the side farther from the equator is grounded later during rotation (forward rotation) of the tire, the side wall on the kick-out side The angle α gradually increases from the side closer to the tire equator to the side farther from the equator, but this contributes to the suppression of wear due to the displacement during kicking described above on the side closer to the tire equator. This is because the wear rate of the tread rubber is increased because the rate is small.

In the tire according to the present invention, the side wall angles α, β
Is preferably not less than 0 degree and not more than 35 degrees. this is,
If the side wall angle is smaller than 0 degree, the rigidity of the lug is remarkably reduced, and uneven wear may occur. On the other hand, if the side wall angle is larger than 35 degrees, a problem that the volume of the lug is insufficient occurs. In the tire according to the present invention, it is preferable that the side wall angles α and β continuously change from the side far from the tire equator line to the side near the equatorial line. This is because when the side wall angle changes and becomes discontinuous at a certain point,
This is because a difference in rigidity may occur and uneven wear may occur.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pneumatic radial tire for a construction vehicle according to an embodiment of the present invention and a pneumatic radial tire for a construction vehicle according to a comparative example will be described below with reference to the drawings. The tire size is 18.
00R25.

FIG. 1 is a schematic front view showing a tread pattern of a pneumatic radial tire for a construction vehicle according to an embodiment of the present invention. As shown in FIG. 1, the tire according to the embodiment of the present invention extends in the direction inclined in the tire rotation axis direction from the central region of the tread toward either one of the right and left regions, and opens at the tread end TE. One of the lateral grooves 11 and one of the lateral grooves 11 form a pair and extend from the center region of the tread toward the other side region in a direction inclined in the tire rotation axis direction, and the tread end TE
A large number of the lugs 21 and the other lugs 22 are formed in a left and right pair at intervals in the circumferential direction by forming a large number of the other lateral grooves 12 that are open at a distance in the circumferential direction. Equipped tread. One lateral groove 1
1 and the other lateral groove 12 are point-symmetric with respect to a point on the equator line EL of the tire. The sidewall angles α and β are a
Α1 = 19 degrees and β1 = 15 degrees in the -a section, α2 = 16 degrees and β2 = 14 degrees in the bb section and α in the cc section
3 = 14 degrees, β3 = 12 degrees, and the side wall angles α and β
Changes continuously from the side far from the tire equator line EL toward the side close to the equator line EL. In one lug 21 or the other lug 22, when the tire rotates (forward rotation), the side farthest from the tire equator line EL contacts the ground first, and the side closer to the equator line EL contacts the ground later. Is larger than the side wall angle β on the kicking side, and the side wall angle α on the stepping side gradually increases from the side closer to the tire equator EL to the side farther from the equator EL. In one lug 21 or the other lug 22, the side closer to the tire equator line EL first contacts the ground when the tire rotates (forward rotation) and the side farther from the equator line EL contacts the rear, and the side wall angle β on the stepping-in side Is smaller than the side wall angle α on the kicking side, and the side wall angle α on the kicking side is the tire equator line EL.
From the side closer to the equator line EL gradually increases.

Here, the relationship between the rotation (forward rotation) direction of the tire and the stepping side and kicking side will be described with reference to FIG. As shown in FIG. 2 (A), when the rotation (forward rotation) direction RD of the tire is an upward direction, the side of one lug 21 or the other lug 22 farther from the tire equator line EL is grounded first. The lug whose side closer to the equator EL is grounded later is the lug 21, the lug closer to the tire equator EL first and grounded farther away from the equator EL is the lug 22, and the lug 21 is depressed. Side refers to 21A, the kicking side of lug 21 refers to 21B, and lug 22
The stepping side of the lug 22A refers to 22A, and the kicking side of the lug 22 refers to 22B. Conversely, as shown in FIG. 2 (B), when the rotation (forward rotation) direction RD of the tire is a downward direction, the side of the one lug 21 or the other lug 22 that is farther from the tire equator line EL comes first. The lug which is in contact with the ground and the side closer to the equator line EL is the lug 22 is the tire equator line EL.
The lug whose first side is grounded first and whose side farther from the equator line EL is grounded is the lug 21, the stepping side of the lug 22 indicates 22B, the kicking side of the lug 22 indicates 22A, and the lug 21 Stepping side refers to 21B, and lug 21
Kicker side means 21A.

In the conventional tire, the side wall angles α and β are α1 = β1 = 16 degrees in the aa section, α2 = β2 = 14 degrees in the bb section, and α3 = β3 = 12 in the cc section.
Degree, and is almost the same as the tire of the above embodiment except that the side wall angle on the stepping side and the kicking side is the same.

The pneumatic radial tire for a construction vehicle according to the above embodiment and the pneumatic radial tire for a construction vehicle according to the prior art described above.
For tires, a comparative test of wear resistance was performed by an indoor drum test.

According to the results of the comparative test, the tire of the above example had a 12% reduction in the rate of wear development as compared with the conventional tire.

[0016]

From the results of the above comparative tests, it can be seen that the present invention can provide a pneumatic tire having excellent wear resistance.

[Brief description of the drawings]

FIG. 1 is a schematic front view showing a tread pattern of a tire of the present invention.

FIG. 2 is a drawing for explaining the relationship between the rotation (forward rotation) direction of a tire and a stepping side and a kicking side.

[Explanation of symbols]

 11 One lateral groove 12 The other lateral groove 21 One lug 22 The other lug EL Equatorial line of tire RD Tire rotation (forward rotation) direction TE Tread end

Claims (3)

[Claims] 1. A left or right lateral groove extending in a direction inclined in the tire rotation axis direction from a central region of a tread toward one of right and left side regions and opening at a tread end; Paired with the direction groove, extending from the central region of the tread toward the other side region in the direction inclined in the tire rotation axis direction, and the other lateral groove opening at the tread end is spaced circumferentially. In the pneumatic tire provided with a large number of treads, one lug and the other lug are formed in a left-right pair at circumferential intervals with respect to each other. (1) The one lateral groove And the other lateral groove are point-symmetric with respect to a point on the equator line of the tire, and (2) the one lug or the other lug
In a lug where the side farther from the tire equator is grounded first and the side closer to the equator is grounded later when the tire rotates (forward rotation),
The side wall angle α on the stepping side is larger than the side wall angle β on the kicking side, and the side wall angle α on the stepping side gradually increases from the side closer to the tire equator to the side farther from the equator. In one lug or the other lug, when the tire rotates (forward rotation), the side closer to the tire equator is grounded first, and the side farther from the equator is grounded later, and the side wall angle β on the stepping side kicks out. A heavy-duty pneumatic tire characterized in that the side wall angle α is smaller than the side wall angle α and the side wall angle α on the kicking side gradually increases from the side closer to the tire equator line to the side farther from the equator line. 2. The pneumatic tire according to claim 1, wherein the side wall angles α and β are 0 degrees or more and 35 degrees or less. 3. The pneumatic tire according to claim 1, wherein the side wall angle continuously changes from a side far from the tire equator to a side near the equator.