WO2013088726A1

WO2013088726A1 - Pneumatic tire

Info

Publication number: WO2013088726A1
Application number: PCT/JP2012/007979
Authority: WO
Inventors: 高橋　淳一
Original assignee: 株式会社ブリヂストン
Priority date: 2011-12-13
Filing date: 2012-12-13
Publication date: 2013-06-20
Also published as: CN103998257B; JP6163106B2; AU2012353879B2; AU2012353879A1; CN103998257A; JPWO2013088726A1

Abstract

The purpose of the present invention is to provide a pneumatic tire with improved dirt discharge capability. In this pneumatic tire, lug grooves that extend in the width direction of the tire and open at one end to the edge of the tread are formed in the tread surface. The pneumatic tire is characterized in that at least one of the groove walls, located on either side in the circumferential direction of the tire, of each lug groove has a curved-surface section comprising a curved surface of a prescribed shape, and in that in the curved surface of the prescribed shape, a cross-sectional curved line perpendicular to the edge of the lug groove open to the tread surface or to a line extending from this open edge is a curved line that is convex in the direction opposite to that of the lug groove side, while the curvature of the cross-sectional curved line becomes gradually smaller as it proceeds from the tire equator toward the edge of the tread.

Description

Pneumatic tire

The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved soil removal performance.

In general, tires mounted on vehicles that run in muddy areas have traction performance that catches and kicks mud by grooves formed on the tread surface, and discharges mud from the grooves so that the caught mud does not clog the grooves. There is a demand for soil removal performance.

Therefore, conventionally, as a light truck tire traveling in a muddy area, a lug groove extending in the tire width direction and having one end opened at the tread end is formed on the tread surface, so that mud can be caught and kicked out by the lug groove. Tires that have been used are used. Also, as a tire that can suppress mud clogging in the lug groove, the groove wall angle of the lug groove (angle formed by the tread part tread surface and the lug groove wall wall) gradually increases from the tire equator side toward the tread end side. A pneumatic tire is proposed (see, for example, Patent Document 1). Specifically, Patent Document 1 proposes a pneumatic tire in which the amount by which the wall of the lug groove falls toward the land portion located between the lug grooves gradually increases toward the tread end side. Yes. In this pneumatic tire, since the groove width of the lug groove is gradually increased toward the tread end side and the tire radial direction outer side, the mud that has entered the lug groove is Easily discharged outward in the tire radial direction.

JP 2001-55014 A

However, the conventional pneumatic tire in which the groove wall angle of the lug groove is increased on the tread end side cannot sufficiently improve the soil removal performance. Then, an object of this invention is to provide the pneumatic tire which improved the soil removal performance.

SUMMARY OF THE INVENTION An object of the present invention is to advantageously solve the above-described problems, and the pneumatic tire according to the present invention forms a lug groove extending in the tire width direction and having one end opened at the tread end on the tread portion tread surface. In the pneumatic tire, at least one of the groove walls located on both sides in the tire circumferential direction of the lug groove has a curved surface portion formed of a curved surface of a predetermined shape, and the curved surface of the predetermined shape is The cross-sectional curve in the direction perpendicular to the opening edge to the tread surface or the extension line of the opening edge is a convex curve toward the side opposite to the lug groove side, and the curvature of the cross-sectional curve is the tire equator The curved surface gradually decreases from the side toward the tread end side.
In the present invention, “extending in the tire width direction” means extending in the tire width direction, and “extending in the tire width direction” is inclined with respect to a direction parallel to the tire width direction. The case of extending is also included. In the present invention, “the curvature of the cross-sectional curve gradually decreases” means that the cross-sectional curve is formed in the width direction (that is, the opening edge to the tread surface of the lug groove or an extension line of the opening edge in the curved surface portion). When the curvatures at positions that are equally divided (eg, equally divided into two equal parts, three equal parts, four equal parts, etc.) in the height direction (that is, the tire radial direction) are compared, the curvature gradually decreases. It points to become.

According to the pneumatic tire of the present invention, it is possible to sufficiently improve the soil removal performance when traveling in a muddy ground.

1 is a plan view of a part of a tread portion of a typical pneumatic tire according to the present invention. It is an enlarged plan view which expands and shows the shoulder side block land part of the pneumatic tire shown in FIG. (A) is the figure which looked at the shoulder side block land part shown in FIG. 2 from the direction of the arrow A shown in FIG. 2, (b) is the arrow which shows the shoulder side block land part shown in FIG. 2 in FIG. It is the figure seen from the direction of B. FIG. 3 is a view showing a cross section of a shoulder block land portion shown in FIG. 2, (a) showing a cross section taken along line II, (b) showing a cross section taken along line II-II, and (c). Indicates a cross section along the line III-III. 4A and 4B are views showing a cross section of the shoulder block land portion shown in FIG. 2, where FIG. 4A shows a cross section taken along line IV-IV, and FIG. 4B shows a cross section taken along line VV.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The pneumatic tire of the present invention has excellent soil removal performance, and can be particularly suitably used when traveling in a muddy area.

Here, FIG. 1 is a plan view of a part of a tread portion of an example of the pneumatic tire of the present invention. The pneumatic tire shown in FIG. 1 can be suitably used as a light truck tire without any particular limitation.

Here, as shown in FIG. 1, the tread portion tread 100 of an example of the pneumatic tire of the present invention has one central main groove 1 extending in the tire circumferential direction on the tire equator CL, and a central main groove 1. A total of two

main grooves

2 and 2 are formed which are located on both outer sides in the tire width direction (tread end TE side) and extend in the tire circumferential direction. Further, the tread portion tread 100 has a plurality of lug grooves 3 extending in the tire width direction between the main groove 2 and the tread end TE, a central main groove 1, and a main groove adjacent to the central main groove 1 ( A plurality of lateral grooves 4 extending in the tire width direction are formed between the adjacent main grooves) 2.
In the present invention, “extending in the tire circumferential direction” means extending in the tire circumferential direction, and “extending in the tire circumferential direction” is inclined with respect to a direction parallel to the tire circumferential direction. The case of extending is also included.

The tread portion tread 100 has a shoulder side block land portion 10 defined by the main groove 2, the lug groove 3 and the tread end TE, and a center formed by the central main groove 1, the main groove 2 and the lateral groove 4. A side block land portion 20 is provided.

Here, the central main groove 1 is not particularly limited, and is substantially linear in a plan view and extends continuously in the tire circumferential direction. In the pneumatic tire of the present invention, the central main groove may be a zigzag groove in plan view. In the pneumatic tire of the present invention, the position where the central main groove is formed is not limited to the tire equator CL. Incidentally, it is preferable that the central main groove is formed in a range in which the drainage performance of the tire can be sufficiently secured, for example, in the central portion of the tread portion tread. If the central main groove is formed in the center of the tread surface, the load applied to the tire is small and the ground contact area of the tire is small, such as when no load is loaded on a vehicle equipped with a tire (when empty) This is because sufficient drainage performance can be ensured by the central main groove even under conditions. The central main groove is preferably a linear groove in plan view with good drainage performance.

The pair of

main grooves

2 and 2 positioned with the central main groove 1 interposed therebetween is not particularly limited, and is substantially zigzag in a plan view and continuously extends in the tire circumferential direction. In the pneumatic tire of the present invention, the main groove may be a groove that is linear in a plan view.

The lug groove 3 has one end opened to the tread end TE and the other end opened to the main groove 2. The lug grooves 3 are not particularly limited, and the plan view shape is a curved shape that is convex toward one side in the tire circumferential direction, and extends in an inclined manner with respect to a direction parallel to the tire width direction.

The lateral groove 4 has one end opened to the central main groove 1 and the other end opened to a main groove (adjacent main groove) 2 adjacent to the central main groove 1 and extending in the tire circumferential direction. The lateral groove 4 is not particularly limited, and has a curved shape in plan view and extends with an inclination with respect to a direction parallel to the tire width direction. Moreover, the opening width to the tread part tread surface 100 of the horizontal groove 4 is not specifically limited, It is narrow at the center main groove 1 side. The “opening width of the lateral grooves 4” refers to the distance along the tire circumferential direction between the opening edges of the lateral grooves 4.

The shoulder block land portion 10 formed on the tread portion tread 100 of the pneumatic tire of this example has a substantially trapezoidal tread shape. Further, the center side block land portion 20 formed on the tread portion tread surface 100 has a substantially triangular sail shape on the tread surface shape.

Here, in the pneumatic tire of this example, the groove walls located on both sides in the tire circumferential direction of the lug grooves 3, that is, the side walls on both sides in the tire circumferential direction of the shoulder side block land portion 10 have a predetermined shape. Specifically, the groove wall located on one side in the tire circumferential direction of the lug groove 3 has a curved surface portion 35 formed of a curved surface having a predetermined shape. Moreover, the groove wall located in the tire circumferential direction other side of the lug groove 3 has the taper part 36 which consists of a predetermined-shaped taper surface.
In the pneumatic tire of the present invention, the shape of the other groove wall may be an arbitrary shape as long as at least one of the groove walls of the lug groove has a curved surface portion. In the pneumatic tire of the present invention, when a curved surface portion or a tapered portion is provided on the groove wall, the curved surface portion or the tapered portion may be provided over the entire width of the groove wall, or the curved surface portion is provided only on a part of the groove wall. Alternatively, a tapered portion may be provided. Note that, from the viewpoint of maximizing the effect obtained by providing the curved surface portion and the tapered portion, the curved surface portion and the tapered portion are preferably provided over the entire width of the groove wall.

The curved surface portion 35 is shown in an enlarged plan view of the shoulder side block land portion 10 in FIG. 2, and FIG. 3A shows a view of the shoulder side block land portion 10 seen from the direction of the arrow A shown in FIG. Thus, the lug groove 3 is provided over substantially the entire width of the groove wall located on one side in the tire circumferential direction.
1, 2, and 3 (a), the groove wall having the curved surface portion 35 is inclined so that the height of the lug groove 3 from the groove bottom gradually decreases toward the main groove 2 side. A portion 37 is provided on the opening side of the lug groove 3 to the main groove 2. More specifically, the groove wall having the curved surface portion 35 is an extension line of the outer edge in the tire radial direction of the side wall on the main groove 2 side of the shoulder side block land portion 10 in a plan view of the shoulder side block land portion 10. An inclined portion 37 is provided at a portion surrounded by a virtual line (not shown) orthogonal to the opening edge 31 through the main groove side end of the opening edge 31 of the lug groove 3 and the tire wall inner end edge of the groove wall. Have. The curved surface portion 35 extends over substantially the entire width of the groove wall including the inclined portion 37.

Then, as shown in FIGS. 4 (a) to 4 (c), cross sections taken along lines II, II-II, and III-III in FIG. The following conditions (1) and (2) are satisfied.
(1) In the cross-sectional view in the direction orthogonal to the opening edge 31 of the lug groove 3 on the tread portion tread surface 100 or the extension line EL of the opening edge 31, the curved sectional curve 35A is opposite to the lug groove 3 side ( It consists of a convex curve toward the shoulder-side block land portion 10).
(2) The curvature of the cross-sectional curve 35A gradually decreases from the tire equator CL side toward the tread end TE side.

Further, as shown in FIGS. 2 and 4 (a) to (c), in the pneumatic tire of this example, the curved surface of the predetermined shape forming the curved surface portion 35 also satisfies the following conditions (3) and (4). ing.
(3) The distance in the direction orthogonal to the tire radial direction line between the tire radial direction line 35A and the tire radial direction line passing through the tire radial direction outer end 35B of the cross sectional curve 35A gradually increases inward in the tire radial direction. become longer. That is, the groove wall of the lug groove 3 is inclined in a direction in which the shoulder side block land portion 10 protrudes into the lug groove 3.
(4) In plan view of the tread portion tread 100, between the opening edge 31 of the lug groove 3 to the tread portion tread 100 or the extension line EL of the opening edge 31 and the tire radial direction inner end edge 33 of the curved portion 35. The distance in the direction orthogonal to the opening edge 31 or the extension line EL of the opening edge 31 gradually decreases from the tire equator CL side toward the tread end TE side.

The curved surface having the predetermined shape described above is not particularly limited, and the cross-sectional curve 35A in the direction perpendicular to the opening edge 31 of the lug groove 3 or the extension line EL of the opening edge 31 has the following conditions (5) to ( The curved surface which consists of the curve which satisfy | fills 7) can be mentioned.
(5) A line that bisects the cross-sectional curve 35A in the cross-sectional width direction (direction parallel to the opening edge 31 or the direction perpendicular to the extension line EL of the opening edge 31) and the cross-sectional curve 35A in the cross-section height direction (tire diameter) Pass through an intersection P with a line located on the innermost side in the tire radial direction among the three lines equally divided into four directions.
(6) The tire radial direction outer end 35B is in contact with a line (tire radial direction line) extending in the cross-section height direction.
(7) The tire radial inner end 35C is in contact with a line extending in the cross-sectional width direction (a line parallel to the opening edge 31 of the lug groove 3 or the line orthogonal to the extension line EL of the opening edge 31).

Further, the tapered portion 36 is an enlarged plan view of the shoulder side block land portion 10 shown in FIG. 2, and the shoulder side block land portion 10 shown in FIG. 3B as seen from the direction of arrow B shown in FIG. As shown, the lug groove 3 is provided over the entire width of the groove wall located on the other side in the tire circumferential direction.

As shown in FIG. 2, the tapered portion 36 has an opening edge 32 (an opening on the opposite side of the tire circumferential direction from the opening edge 31) to the tread portion tread surface 100 of the lug groove 3 in a plan view of the tread portion tread surface 100. The length in the direction orthogonal to the edge is gradually increased from the tire equator CL side toward the tread end TE side. As shown in FIG. 3B, the tapered portion 36 has a height from the groove bottom of the lug groove 3 (that is, a height from the inner edge 34 in the tire radial direction of the groove wall) on the tire equator CL side. It gradually becomes lower from the tread end TE side.
In addition, as shown in FIGS. 5 (a) and 5 (b), cross sections taken along lines IV-IV and VV in FIG. 2, respectively, of the groove wall located on the other side in the tire circumferential direction of the lug groove 3, Portions other than the taper portion 36 extend along the tire radial direction.

Further, in the pneumatic tire of this example, as shown in FIG. 1, a protruding portion 21 that protrudes toward the lateral groove 4 located on one side in the tire circumferential direction of the center side block land portion 20 on the center side block land portion 20. Is provided. More specifically, a projecting portion 21 having a substantially triangular shape in plan view protruding toward the inside of the lateral groove 4 is provided at a portion of the center side block land portion 20 on one side in the tire circumferential direction and on the central main groove 1 side. ing. And by this projection part 21, the opening width of the horizontal groove 4 is narrowed by the center main groove 1 side.
In the pneumatic tire of the present invention, the protrusions may be provided on both sides in the tire circumferential direction of the center side block land portion.

Further, in the pneumatic tire of this example, as shown in FIG. 1, the protruding portion 21 of the side wall of the center side block land portion 20 on the side where the protruding portion 21 is provided, that is, the groove wall of the lateral groove 4 is provided. The groove wall on the side to be located is not particularly limited, and is composed of a curved surface 41 whose length in the direction orthogonal to the extending direction of the lateral groove 4 gradually increases toward the protruding portion 21 side.

According to the pneumatic tire of this example, one of the groove walls of the lug groove 3 has the curved surface portion 35 made of a curved surface with a predetermined shape, so that the running performance in a muddy place (particularly, traction performance). The soil removal performance can be sufficiently enhanced while ensuring That is, in this example pneumatic tire, the groove wall of the lug groove 3 is not a curved surface having a constant curvature or a flat surface having a constant inclination angle with respect to the tread surface, and is convex toward the side opposite to the lug groove 3 side, And since it has the curved surface part 35 which consists of a curved surface in which a curvature becomes small gradually toward the tread end TE side, the change in the curvature of the curved surface part 35 is utilized, and the soil removal performance is ensured while ensuring the traction performance. It can be raised enough. Specifically, on the tire equator CL side, the curvature of the cross-sectional curve 35A of the curved surface portion 35A is increased (the radius of curvature is decreased), and the groove wall is laid down, so that the tire equator CL side in the lug groove 3 when traveling on muddy ground. This makes it easier to catch mud and ensure traction performance. Moreover, the groove volume of the lug groove 3 is ensured by decreasing the curvature of the cross-sectional curve 35A of the curved surface portion 35 on the tread end TE side (increasing the radius of curvature) and raising the groove wall. Mud can be easily discharged. Furthermore, the curvature of the cross-sectional curve 35A of the curved surface portion 35 is gradually decreased toward the tread end side, and the shape of the groove wall provided with the curved surface portion 35 is changed in a three-dimensional manner, so that it is captured in the lug groove 3. The generated mud (mud column) can be facilitated to be discharged toward the tread end side as the tire rotates.

Further, in this example pneumatic tire, the curved surface of the predetermined shape forming the curved surface portion 35 satisfies the conditions (3) and (4) described above. That is, the groove wall of the lug groove 3 is inclined in a direction in which the shoulder side block land portion 10 protrudes into the lug groove 3. Therefore, in the pneumatic tire of this example, compared to the case where the lug groove 3 is formed so that the shoulder side block land portion 10 is swollen in the tire circumferential direction, the curved surface of the predetermined shape constituting the curved surface portion 35 is a smooth curved surface. As a result, the soil removal performance can be further enhanced.

Furthermore, in this example pneumatic tire, the inclined portion 37 is provided on the groove wall of the lug groove 3, and the curved surface portion 35 extends over the inclined portion 37. Accordingly, in this example pneumatic tire, the slanted portion 37 located at the position where the groove wall of the lug groove 3 is extended toward the main groove 2 side makes it easier to catch mud in the lug groove 3 and improves the traction performance. Can be improved. Moreover, the curved surface of a predetermined shape can be extended widely to the main groove 2 side, and the soil removal performance can be sufficiently enhanced.

In the pneumatic tire of this example, the curved wall 35 is provided on one of the groove walls of the lug groove 3, and the tapered part 36 is provided on the other groove wall. The soil removal performance can be sufficiently enhanced while suppressing a significant decrease in volume. That is, when the curved surface portions 35 are provided on both the groove walls of the lug groove 3, the groove volume of the lug groove 3 may be reduced on the tire equator CL side having a large curvature, but the curved surface is formed only on one groove wall. If the part 35 is provided, the drop of the groove volume of the lug groove 3 can be suppressed. Moreover, if the taper part 36 is provided in the other groove wall, the discharge of mud in the lug groove 3 can be promoted by the inclined surface of the taper part 36 as compared with the case where the taper part 36 is not provided.

Furthermore, in this example pneumatic tire, since the central main groove 1 is formed in the tread portion tread surface 100, the drainage performance of the tire can be sufficiently enhanced.
Further, in the pneumatic tire of this example, the protrusion 21 is formed on the center side block land portion 20 and the opening width of the lateral groove 4 is narrowed on the central main groove 1 side. It is possible to prevent mud from flowing into the central main groove 1 from the TE side. Therefore, it can suppress that the center main groove 1 obstruct | occludes with mud, and it becomes impossible to obtain desired drainage performance. Incidentally, in the pneumatic tire of this example, the groove wall on the side where the protruding portion 21 is located is formed by the curved surface 41 in the groove wall of the lateral groove 4, while ensuring the rigidity of the center side block land portion 20, The protrusion 21 can be formed.

As mentioned above, although the pneumatic tire of this invention was demonstrated with reference to drawings, the pneumatic tire of this invention is not limited to the said example. And a change can be suitably added to the pneumatic tire of this invention.

According to the present invention, it is possible to provide a pneumatic tire with sufficiently improved soil removal performance when traveling in a muddy ground.

1 Central main groove 2 Main groove (adjacent main groove)
3 Lug groove 4 Horizontal groove 10 Shoulder side block land part 20 Center side block land part 21 Projection part 31 Open edge 32 Open edge 33 Tire radial inner edge 34 Tire radial inner edge 35 Curved part 35A Cross section curve 35B Tire radial direction Outer end 35C Tire radial inner end 36 Tapered portion 37 Inclined portion 41 Curved surface 100 Tread portion tread

Claims

A pneumatic tire in which a tread portion tread has a lug groove extending in the tire width direction and having one end opened to the tread end,
At least one of the groove walls located on both sides in the tire circumferential direction of the lug groove has a curved surface portion formed of a curved surface of a predetermined shape,
The curved surface of the predetermined shape is a curved curve in a direction perpendicular to the opening edge to the tread portion tread surface of the lug groove or an extension line of the opening edge, and is a convex curve toward the side opposite to the lug groove side, A pneumatic tire characterized in that the curvature of the cross-sectional curve is a curved surface that gradually decreases from the tire equator side toward the tread end side.
The distance in the direction perpendicular to the tire radial direction line between the tire radial direction line passing through the tire radial direction outer end of the cross sectional curve and the cross sectional curve gradually increases inward in the tire radial direction,
In plan view of the tread portion tread, the opening edge between the opening edge of the lug groove to the tread portion tread surface or an extension line of the opening edge and the tire radial direction inner end edge of the curved surface portion or the tread portion tread surface 2. The pneumatic tire according to claim 1, wherein a distance in a direction perpendicular to the extension line of the opening edge gradually decreases from the tire equator side toward the tread end side.
The tread has a main groove extending in the tire circumferential direction on the tread surface,
The other end of the lug groove opens into the main groove,
The groove wall having the curved surface portion has an inclined portion on the opening side to the main groove where the height from the lug groove bottom gradually decreases toward the main groove side,
The pneumatic tire according to claim 1, wherein the curved surface portion extends at least over the inclined portion.
The groove wall located on one side in the tire circumferential direction of the lug groove has the curved surface portion,
The groove wall located on the other side in the tire circumferential direction of the lug groove gradually decreases in height from the lug groove bottom toward the tread end side from the tire equator side, and in a plan view of the tread portion tread surface, 4. The taper portion of the lug groove having a taper portion whose length in a direction perpendicular to the opening edge to the tread portion tread gradually increases from the tire equator side toward the tread end side. The pneumatic tire according to Crab.
The pneumatic tire according to any one of claims 1 to 4, further comprising a central main groove extending in a tire circumferential direction at a central portion of the tread portion tread surface.
On the tread portion tread surface, the central main groove, an adjacent main groove that extends adjacent to the central main groove in the tire circumferential direction, and a plurality that extends in the tire width direction between the central main groove and the adjacent main groove A center-side block land portion defined by a lateral groove of
The pneumatic tire according to claim 5, wherein the center-side block land portion has a protrusion that protrudes toward at least a lateral groove located on one side in the tire circumferential direction.