JP2013252808A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving ride comfort performance of the tire, while securing maneuvering stability performance of the tire.SOLUTION: A pneumatic tire 1 includes a rim protecting bar 2 in a sidewall part. The rim protecting bar 2 has a three-dimensional sipe 21 extending in the tire circumferential direction. The three-dimensional sipe 21 has a zigzag shape or a waveform of extending inside in the tire width direction along a reference line S of the rim protecting bar 2. The three-dimensional sipe 21 has a zigzag shape or a waveform of extending in the tire circumferential direction.

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the riding comfort performance of the tire while ensuring the steering stability performance of the tire.

  In recent years, pneumatic tires are provided with rim protection bars on the sidewalls in order to improve rim cut resistance. In the configuration including such a rim protect bar, the rigidity of the sidewall portion is higher than that of the rim protect bar, so that there is a problem that riding comfort performance is likely to deteriorate.

  As a conventional pneumatic tire related to such a problem, a technique described in Patent Document 1 is known.

JP-A-10-138718

  It is an object of the present invention to provide a pneumatic tire that can improve the riding comfort performance of the tire while ensuring the steering stability performance of the tire.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire including a rim protect bar in a sidewall portion, and the rim protect bar has a three-dimensional sipe extending in a tire circumferential direction. It is characterized by that.

  In the pneumatic tire according to the present invention, since the rim protect bar has a three-dimensional sipe extending in the tire circumferential direction, the rigidity of the sidewall rubber in the tire radial direction is reduced. Thereby, there exists an advantage which the riding comfort performance of a tire improves. Further, since the rim protect bar is continuous in the tire circumferential direction, the rigidity of the sidewall rubber with respect to the tire circumferential direction is ensured. Thereby, there exists an advantage by which the steering stability performance of a tire is ensured.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged sectional view showing a rim protect bar of the pneumatic tire shown in FIG. FIG. 3 is a side view showing a rim protect bar of the pneumatic tire shown in FIG. FIG. 4 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. FIG. 5 is an explanatory diagram showing a specific example of the three-dimensional sipe shown in FIG. FIG. 6 is an explanatory diagram showing a specific example of the three-dimensional sipe shown in FIG. FIG. 7 is an explanatory diagram showing a specific example of the three-dimensional sipe shown in FIG. FIG. 8 is an explanatory diagram showing a specific example of the three-dimensional sipe shown in FIG. FIG. 9 is an explanatory diagram showing a specific example of the three-dimensional sipe shown in FIG. FIG. 10 is an explanatory diagram showing a specific example of the three-dimensional sipe shown in FIG. FIG. 11 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. Further, the constituent elements of this embodiment include those that can be replaced while maintaining the identity of the invention and that are obvious for replacement. In addition, a plurality of modifications described in this embodiment can be arbitrarily combined within a range obvious to those skilled in the art.

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire 1 according to an embodiment of the present invention. FIG. 1 shows a passenger car radial tire having a rim protect bar as an example of the pneumatic tire 1. Reference sign CL is a tire equator plane.

  The pneumatic tire 1 includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair. Rim cushion rubbers 17 and 17 (see FIG. 1).

  The pair of bead cores 11 and 11 has an annular structure and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11 to reinforce the bead portion.

  The carcass layer 13 is bridged in a toroidal shape between the left and right bead cores 11 and 11 to form a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass layer 13 is formed by rolling a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coat rubber and having an absolute value of 85 [deg]. A carcass angle of 95 [deg] or less (inclination angle in the fiber direction of the carcass cord with respect to the tire circumferential direction). In the configuration of FIG. 1, the carcass layer 13 has a two-layer structure in which two carcass plies are stacked. However, the present invention is not limited to this, and the carcass layer 13 may have a single layer structure.

  The belt layer 14 is formed by laminating a pair of cross belts 141 and 142, and is arranged around the outer periphery of the carcass layer 13. The pair of cross belts 141 and 142 is formed by rolling a plurality of belt cords made of steel or organic fiber material with a coating rubber, and having a belt angle of 10 [deg] or more and 30 [deg] or less in absolute value. Have. Further, the pair of cross belts 141 and 142 have belt angles with different signs from each other (inclination angle of the fiber direction of the belt cord with respect to the tire circumferential direction), and are laminated so that the fiber directions of the belt cords cross each other. (Cross ply structure).

  The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of rim cushion rubbers 17 and 17 are arranged on the outer sides in the tire width direction of the left and right bead cores 11 and 11 and the bead fillers 12 and 12, respectively, and constitute left and right bead portions.

[Rim protect bar on the side wall]
The pneumatic tire 1 includes a rim protect bar 2 (see FIG. 1). The rim protect bar 2 is a protrusion for protecting the rim, and is formed on the sidewall portion. Specifically, the rim protect bar 2 has a shape that protrudes outward in the tire width direction from the profile of the sidewall portion, and continuously extends in the tire circumferential direction and has an annular structure as a whole. Further, the rim protect bar 2 is in the tire radial direction outer side than the maximum radial direction position of the rim (not shown) and in the tire radial direction inner side than the maximum width position of the sidewall portion profile in the tire rim assembled state. Moreover, it protrudes outward in the tire width direction from the maximum width position of the rim. The rim protect bar 2 may be disposed on the left and right sidewall portions (see FIG. 1), or may be disposed on only one sidewall portion (not shown). In the latter case, the pneumatic tire 1 is mounted on the vehicle with the sidewall portion having the rim protect bar 2 facing outward in the vehicle width direction.

  In such a configuration, when the tire is mounted on the vehicle, the rim protect bar 2 protrudes outward in the tire width direction from the maximum width position of the rim, whereby contact between the rim and the curb is suppressed. As a result, the rim is protected and the rim cut resistance of the tire is improved.

[3D sipe of rim protect bar]
2 and 3 are an enlarged cross-sectional view (FIG. 2) and a side view (FIG. 3) showing the rim protect bar of the pneumatic tire shown in FIG. In these drawings, FIG. 2 shows a cross-sectional view of the rim protect bar 2 in the tire meridian direction, and FIG. 3 shows a state of the rim protect bar 2 when the side wall portion is viewed in plan.

  In this pneumatic tire 1, as shown in FIGS. 2 and 3, the rim protect bar 2 has a three-dimensional sipe 21 extending in the tire circumferential direction.

  The three-dimensional sipe is a sipe having a sipe wall surface that is bent in the sipe width direction in a cross-sectional view perpendicular to the sipe length direction. Compared with two-dimensional sipe (sipe having a straight sipe wall surface in a cross-sectional view perpendicular to the sipe length direction), the three-dimensional sipe has a strong meshing force between the opposite sipe wall surfaces, so Has the effect of reinforcing. A specific example of the three-dimensional sipe will be described later.

  Here, the maximum height position of the rim protect bar 2 on the basis of the inner peripheral surface of the side wall rubber constituting the rim protect bar 2 in a sectional view in the tire meridian direction is referred to as a vertex P. Therefore, the apex P of the rim protect bar 2 is the position where the sidewall rubber constituting the rim protect bar 2 is the thickest on the surface of the rim protect bar 2. A perpendicular drawn from the vertex P to the inner peripheral line is called a reference line S. The inner peripheral line is a line drawn by the inner peripheral surface of the inner liner 18.

  For example, in the configuration of FIG. 1, the rim protect bar 2 is made of a side wall rubber 16, and the side wall rubber 16 is disposed so as to cover the main body part of the carcass layer 13 and the side surface on the outer side in the tire width direction. As shown in FIG. 2, the rim protect bar 2 has a triangular cross-sectional shape, and the sidewall rubber 16 is the thickest at the apex P thereof.

  At this time, the three-dimensional sipe 21 has a zigzag shape or a wavy shape extending inward in the tire width direction along the reference line S of the rim protect bar 2 in a sectional view in the tire meridian direction (see FIG. 2). The distance (not shown) between the opening of the three-dimensional sipe 21 and the reference line S of the rim protect bar 2 is in the range of 2.0 [mm] or less. Therefore, the three-dimensional sipe 21 may be opened at a position deviated from the vertex P of the rim protect bar 2 (not shown). Further, the bending width A of the three-dimensional sipe 21 is in the range of 0.5 [mm] ≦ A ≦ 4.0 [mm]. The bending width A is measured as the maximum value of the bending width (wave height) of the three-dimensional sipe 21 in the normal direction of the reference line S in a sectional view in the tire meridian direction.

  For example, in the configuration of FIG. 2, the three-dimensional sipe 21 has a zigzag shape in a cross-sectional view in the tire meridian direction, so that opposing sipe wall surfaces have a shape that meshes with each other. The three-dimensional sipe 21 extends inward in the tire width direction with the reference line S as the center of amplitude, and opens at the top of the rim protect bar 2. Further, as shown in FIG. 3, the opening of the three-dimensional sipe 21 is within a range of a predetermined bending width B around the vertex P of the rim protect bar 2. As a result, the three-dimensional sipe 21 divides the rim protect bar 2 vertically into the tire radial direction along the reference line S, and the rigidity of the thick portion of the sidewall rubber 16 is reduced.

  Further, the distance D1 from the opening of the three-dimensional sipe 21 to the inner peripheral surface of the sidewall rubber 16 constituting the rim protect bar 2 and the side wall rubber 16 constituting the rim protect bar 2 from the bottom of the three-dimensional sipe 21. The distance D2 to the inner peripheral surface and the sipe depth D3 of the three-dimensional sipe 21 have a relationship of 1.5 [mm] ≦ D2 and 0.6 ≦ D3 / D1 (see FIG. 2).

  The distance D1 is the thickness of the sidewall rubber 16 at the position where the three-dimensional sipe 21 is disposed. The larger the value, the greater the rigidity of the rim protect bar 2. This distance D1 is uniquely defined by the height of the rim protect bar 2 and the internal structure of the tire (particularly the carcass structure). In the configuration of FIG. 2, the distance D <b> 1 matches the length of the reference line S from the apex P of the rim protect bar 2 to the winding end of the carcass layer 13.

  The distance D2 is a rubber margin of the sidewall rubber 16 at the position where the three-dimensional sipe 21 is arranged. As the distance D2 is larger, a failure due to the separation of the sidewall rubber 16 starting from the three-dimensional sipe 21 is suppressed. The upper limit value of the distance D2 is restricted by the relationship with the lower limit value (0.6 ≦ D3 / D1) of the sipe depth D3 of the three-dimensional sipe 21.

  The sipe depth D3 is the depth of the three-dimensional sipe 21 in the thickness direction of the sidewall rubber 16, and the larger the value, the larger the sipe area, and the rigidity of the thick portion of the sidewall rubber 16 is reduced. The The sipe depth D3 has a relationship of D3 = D1-D2 with respect to the distances D1 and D2. For this reason, the upper limit value of the sipe depth D3 (ratio D3 / D1) is restricted by the relationship with the lower limit value (1.5 [mm] ≦ D2) of the distance D2.

  In the configuration of FIG. 2, the sidewall rubber 16 is adjacent to the winding end of the carcass layer 13 on the reference line S of the three-dimensional sipe 21. For this reason, the distances D <b> 1 and D <b> 2 are measured with reference to the adjacent surface between the sidewall rubber 16 and the rolled-up end of the carcass layer 13. However, the present invention is not limited to this, and when the sidewall rubber 16 and the main body portion of the carcass layer 13 are adjacent on the reference line S, and the sidewall rubber 16 and the bead filler 12 are adjacent on the reference line S. In this case, the distances D1 and D2 are measured with reference to these adjacent surfaces (not shown).

  Moreover, the three-dimensional sipe 21 has a zigzag shape or a wavy shape extending in the tire circumferential direction in a plan view of the sidewall portion (see FIG. 3). The wavelength (period) L of the three-dimensional sipe 21 is in the range of 2.0 [mm] ≦ L ≦ 4.0 [mm]. Further, the bending width B of the three-dimensional sipe 21 is in the range of 0.5 [mm] ≦ B ≦ 4.0 [mm]. The bending width B is measured as the maximum value of the bending width of the three-dimensional sipe 21 in the tire radial direction in a plan view of the sidewall portion.

  For example, in the configuration of FIG. 3, when the three-dimensional sipe 21 has a zigzag shape in a plan view of the sidewall portion, opposing sipe wall surfaces have a shape that meshes with each other. The three-dimensional sipe 21 extends in the tire circumferential direction with the vertex P of the rim protect bar 2 as the center of amplitude. Thereby, the three-dimensional sipe 21 divides the rim protect bar 2 into two in the tire radial direction around the apex P, and the rigidity of the thick portion of the sidewall rubber 16 is reduced. Further, the three-dimensional sipe 21 extends in the tire circumferential direction with a constant wavelength L and a constant amplitude (B / 2), whereby the rigidity of the sidewall rubber 16 in the tire circumferential direction is made uniform.

  Further, the sipe width W of the three-dimensional sipe 21 is in the range of 0.1 [mm] ≦ W ≦ 1.0 [mm]. The sipe width W is measured in an uninflated state of the tire.

  Even when the tire is mounted on the specified rim and applied with the specified internal pressure and the specified load is applied, the sipe wall surfaces of the three-dimensional sipe 21 are separated from each other and the three-dimensional sipe 21 is opened. Become.

  Here, the prescribed rim refers to “applied rim” prescribed in JATMA, “Design Rim” prescribed in TRA, or “Measuring Rim” prescribed in ETRTO. The specified internal pressure means “maximum air pressure” specified by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. The specified load means the “maximum load capacity” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “LOAD CAPACITY” defined by ETRTO. However, in JATMA, in the case of tires for passenger cars, the specified internal pressure is air pressure 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  In this pneumatic tire 1, the rim protect bar 2 has the three-dimensional sipe 21, whereby the rigidity of the sidewall rubber 16 is reduced. Specifically, when the three-dimensional sipe 21 extends in the tire circumferential direction along the rim protect bar 2, the rim protect bar 2 is divided in the tire radial direction, and the rigidity of the sidewall rubber 16 with respect to the tire radial direction is increased. Is reduced. Thereby, the riding comfort performance of a tire improves. On the other hand, since the rim protect bar 2 is continuous in the tire circumferential direction, the rigidity of the sidewall rubber 16 with respect to the tire circumferential direction is ensured. Further, for example, when the sidewall portion is bent in the tire width direction when the vehicle is turning, the sipe wall surfaces of the three-dimensional sipe 21 are engaged with each other in the tire width direction, so that the rigidity of the sidewall rubber 16 with respect to the tire width direction is increased. Will increase. As a result, the steering stability performance of the tire is appropriately ensured.

[Modification]
FIG. 4 is an explanatory view showing a modified example of the pneumatic tire shown in FIG. 1. The figure shows a cross-sectional view of the rim protect bar 2 in the tire meridian direction.

  In the configuration of FIG. 2, the rim protect bar 2 has a triangular cross-sectional shape, and a three-dimensional sipe 21 is opened at the apex P thereof.

  However, the present invention is not limited to this, and the rim protect bar 2 may have a trapezoidal cross-sectional shape having a flat top as shown in FIG. Even in such a configuration, the maximum height position of the rim protect bar 2 with respect to the inner peripheral surface of the side wall rubber constituting the rim protect bar 2 is the apex P in a sectional view in the tire meridian direction. At this time, if there is a width at the maximum height position of the rim protect bar 2, the central portion of the width is set as the apex P. Further, a perpendicular drawn from the apex P to the inner peripheral line becomes the reference line S.

[Specific example of 3D sipe]
5-10 is explanatory drawing which shows the specific example of the three-dimensional sipe described in FIG. In these drawings, FIGS. 5, 6, and 8 to 10 are transparent perspective views of the sipe wall surface of the three-dimensional sipe 21, and FIG. 7 is a plan view of the three-dimensional sipe 21.

  In the configuration of FIG. 3, the three-dimensional sipe 21 has a zigzag shape extending in the tire circumferential direction along the apex P of the rim protect bar 2 in a plan view of the sidewall portion. As such a three-dimensional sipe 21, for example, the three-dimensional sipe 21 described in FIGS. 5 and 6 can be adopted.

  In the three-dimensional sipe 21 of FIG. 5, the sipe wall surface has a structure in which a triangular pyramid and an inverted triangular pyramid are connected in the sipe length direction. In other words, the sipe wall surface has unevenness that face each other between the zigzag shape on the opening side and the bottom side by shifting the zigzag shape on the opening side and the zigzag shape on the bottom side in the tire width direction. Have. Further, the sipe wall surface is an unevenness when viewed in the tire radial direction in these unevennesses, between the convex bending point on the opening side and the concave bending point on the bottom side, the concave bending point on the opening side and the bottom side The convex bending points adjacent to each other between the convex bending points on the opening side and the convex bending point on the bottom side are connected by ridge lines, and the ridge lines are sequentially arranged in the tire circumferential direction. It is formed by connecting in a plane. In addition, one sipe wall surface has an uneven surface in which convex triangular pyramids and inverted triangular pyramids are arranged alternately in the tire width direction, and the other sipe wall surface alternates between concave triangular pyramids and inverted triangular pyramids. Have uneven surfaces arranged in the tire circumferential direction.

  In the three-dimensional sipe 21 of FIG. 6, the sipe wall surface has a structure in which a plurality of prisms having a block shape are connected in the sipe depth direction and the sipe length direction while being inclined with respect to the sipe depth direction. In other words, the sipe wall surface has a zigzag shape at the opening. Further, the sipe wall surface has bent portions that are bent in the tire radial direction at two or more locations in the sipe depth direction inside the rim protect bar 2 and are continuous in the tire circumferential direction, and the sipe depth direction at the bent portion. It has a zigzag shape with amplitude. Further, while the sipe wall surface has a constant amplitude in the tire radial direction, the inclination angle in the tire radial direction with respect to the normal direction of the tread surface is made smaller at the bottom side portion than the opening side portion, and the bent portion The amplitude in the sipe depth direction is made larger at the bottom portion than at the opening portion.

  In addition to the above, as shown in FIG. 7, the three-dimensional sipe 21 extends in the tire circumferential direction along the apex P of the rim protect bar 2 in a plan view of the sidewall portion (the entire tire). The circumference may be circular). As such a three-dimensional sipe 21, for example, a three-dimensional sipe 21 described in FIGS. 8 to 10 may be employed.

  In the three-dimensional sipe 21 of FIG. 8, the sipe wall surface has a zigzag cross-sectional shape extending in the sipe depth direction. In other words, the sipe wall surface is formed by connecting a plurality of types of planes that are inclined at different angles with respect to the sipe depth direction in the tire depth direction. The sipe wall surface has a uniform cross-sectional shape in the tire circumferential direction.

  The three-dimensional sipe 21 in FIG. 9 has a wave shape that repeatedly curves or bends from one end to the other while gradually increasing the bending width as the sipe depth increases. In addition, at a predetermined sipe depth position, a perpendicular line is drawn from both ends of the three-dimensional sipe 21 to a center line passing through the center of the wavy shape bending width of the three-dimensional sipe 21, and the distance between the legs of these perpendicular lines Is a sipe length Ls (not shown). At this time, the sipe length Ls becomes shorter as the sipe depth becomes deeper.

  The three-dimensional sipe 21 in FIG. 10 includes a first offset portion protruding to one side in the sipe width direction, and a second offset portion protruding to the other side in the sipe width direction at a position radially inward of the tire relative to the first offset portion. And have. Also, the sipe length Ls1 (not shown) of the opening and the sipe length Ls2 (not shown) of the bottom have substantially the same relationship (0.95 ≦ Ls2 / Ls1 ≦ 1.05). The peripheral length M1 (not shown) of the opening and the peripheral length M2 (not shown) of the bottom have a relationship of 1.10 ≦ M2 / M1 ≦ 1.50. Further, the planar shape at the bottom of the sipe has a portion parallel to the planar shape at the opening. In addition, the total length P2 (not shown) of the parallel portion and the sipe length Ls1 of the opening have a relationship of 0.20 ≦ P2 / Ls1 ≦ 0.80.

  8 to 10, the opening of the three-dimensional sipe 21 has a straight shape extending in the tire circumferential direction along the vertex P of the rim protect bar 2. Therefore, in these configurations, the wavelength L and the bending width B (see FIG. 3) of the three-dimensional sipe 21 with respect to the tire circumferential direction are the wavelength when the three-dimensional sipe 21 is projected and viewed in the planar view direction of the sidewall portion. Measured as bending width. In the configuration of FIG. 8, since the three-dimensional sipe 21 has a uniform cross-sectional shape in the tire circumferential direction, the three-dimensional sipe 21 does not have the wavelength L and the bending width B.

[effect]
As described above, the pneumatic tire 1 is disposed on the outer side in the tire radial direction of the carcass layer 13, the pair of left and right bead cores 11, 11, the carcass layer 13 spanned between the left and right bead cores 11, 11. Belt layer 14, tread rubber 15 constituting the tread portion, left and right sidewall rubbers 16 and 16 constituting the sidewall portion, left and right rim cushion rubbers 17 and 17 constituting the bead portion, and tire inner peripheral surface The rim protect bar 2 is disposed on the sidewall portion (see FIGS. 1 to 3). The rim protect bar 2 has a three-dimensional sipe 21 extending in the tire circumferential direction.

  In such a configuration, the rim protect bar 2 has the three-dimensional sipe 21 extending in the tire circumferential direction, whereby the rigidity of the sidewall rubber 16 in the tire radial direction is reduced. Thereby, there exists an advantage which the riding comfort performance of a tire improves. Moreover, since the rim protect bar 2 is continuous in the tire circumferential direction, the rigidity of the sidewall rubber 16 with respect to the tire circumferential direction is ensured. Thereby, there exists an advantage by which the steering stability performance of a tire is ensured.

  Moreover, in this pneumatic tire 1, the three-dimensional sipe 21 has a zigzag shape or a wavy shape extending inward in the tire width direction along the reference line S of the rim protect bar 2 (see FIG. 2). In such a configuration, for example, when the sidewall portion is bent in the tire width direction when the vehicle is turning, the sipe wall surfaces of the three-dimensional sipe 21 mesh with each other in the tire width direction, whereby the sidewall rubber 16 with respect to the tire width direction is obtained. Increased rigidity. Thereby, there exists an advantage by which the steering stability performance of a tire is ensured appropriately. Moreover, in such a configuration, since the occurrence of cracks starting from the bottom of the three-dimensional sipe 21 is suppressed, there is an advantage that the durability performance of the tire is improved.

  In the pneumatic tire 1, the distance between the opening of the three-dimensional sipe 21 and the reference line S of the rim protect bar 2 is within a range of 2.0 [mm] or less in a sectional view in the tire meridian direction. Yes (see FIG. 2). In such a configuration, the position of the opening of the three-dimensional sipe 21 at the top of the rim protect bar 2 is optimized, so that there is an advantage that the rigidity of the rim protect bar 2 is appropriately relaxed by the three-dimensional sipe 21.

  In the pneumatic tire 1, the three-dimensional sipe 21 has a zigzag shape or a wavy shape extending in the tire circumferential direction (see FIG. 3). In such a configuration, the rigidity of the sidewall rubber 16 with respect to the tire circumferential direction increases when the sipe wall surfaces of the three-dimensional sipe 21 are engaged with each other in the tire circumferential direction when the vehicle is traveling. Thereby, there exists an advantage by which the steering stability performance of a tire is ensured appropriately.

  Moreover, in this pneumatic tire 1, the wavelength L of the three-dimensional sipe 21 with respect to the tire circumferential direction is in the range of 2.0 [mm] ≦ L ≦ 4.0 [mm] (see FIG. 3). Thereby, there exists an advantage by which the wavelength L of the three-dimensional sipe 21 concerning a tire peripheral direction is optimized. That is, by satisfying 2.0 [mm] ≦ L, the shift of the meshing position of the sipe wall surface when the tire is twisted is suppressed, and the steering stability performance of the tire is ensured. Further, since L ≦ 4.0 [mm], the inclination angle of the sipe wall surface can be increased while the bending width B of the three-dimensional sipe 21 is reduced, so that the meshing action of the sipe wall surface is ensured, and the tire is controlled. Stable performance is ensured.

  Moreover, in this pneumatic tire 1, the bending width B of the three-dimensional sipe 21 with respect to the tire circumferential direction is in the range of 0.5 [mm] ≦ B ≦ 4.0 [mm] (see FIG. 3). Thereby, there exists an advantage by which the bending width B of the three-dimensional sipe 21 concerning a tire peripheral direction is optimized. That is, when 0.5 [mm] ≦ B, the meshing action of the sipe wall surface is ensured, and the steering stability performance of the tire is ensured. Further, by satisfying B ≦ 4.0 [mm], the inclination angle of the sipe wall surface becomes small, wear of the sipe wall surface against repeated bending is suppressed, and the durability performance of the tire is improved.

  Moreover, in this pneumatic tire 1, the bending width A of the three-dimensional sipe 21 with respect to the sipe depth direction is in the range of 0.5 [mm] ≦ A ≦ 4.0 [mm] (see FIG. 2). Thereby, there exists an advantage by which the bending width A of the three-dimensional sipe 21 concerning a sipe depth direction is optimized. That is, when 0.5 [mm] ≦ A, the meshing action of the sipe wall surface is ensured, and the steering stability performance of the tire is ensured. Further, when A ≦ 4.0 [mm], the inclination angle of the sipe wall surface becomes small, wear of the sipe wall surface against repeated bending is suppressed, and the durability performance of the tire is improved.

  Further, in the pneumatic tire 1, the distance D1 from the opening of the three-dimensional sipe 21 to the inner peripheral surface of the sidewall rubber 16 constituting the rim protect bar 2 in the sectional view in the tire meridian direction, and the three-dimensional sipe The distance D2 from the bottom of the rim protect bar 2 to the inner peripheral surface of the sidewall rubber 16 and the sipe depth D3 of the three-dimensional sipe 21 are 1.5 [mm] ≦ D2 and 0.6 ≦ It has a relationship of D3 / D1 (see FIG. 2). In such a configuration, the margin (distance D2) of the sidewall rubber 16 at the bottom of the three-dimensional sipe 21 is appropriately ensured, so that a situation where cracks starting from the bottom of the three-dimensional sipe 21 reach the carcass layer 13 is suppressed. Is done. Thereby, there exists an advantage which the durable performance of a tire improves. Further, since the sipe depth D3 of the three-dimensional sipe 21 is optimized, there is an advantage that the rigidity of the sidewall rubber 16 with respect to the tire radial direction is appropriately reduced and the riding comfort performance of the tire is improved.

  Moreover, in this pneumatic tire 1, the sipe width W of the three-dimensional sipe 21 is in the range of 0.1 [mm] ≦ W ≦ 1.0 [mm] (see FIG. 3). Thereby, there exists an advantage by which the sipe width W of the three-dimensional sipe 21 is optimized. That is, when 0.1 [mm] ≦ W, the rigidity of the sidewall rubber 16 with respect to the tire radial direction is appropriately reduced, and the riding performance of the tire is improved. Further, since W ≦ 1.0 [mm], the meshing of the sipe wall surface of the three-dimensional sipe 21 at the time of tire deformation is ensured, and the steering stability performance of the tire is ensured.

  FIG. 11 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this performance test, evaluations on (1) riding comfort performance, (2) steering stability performance, and (3) durability performance were performed on a plurality of different pneumatic tires (see FIG. 11).

  (1) Riding comfort performance and (2) Steering stability performance were evaluated by attaching a pneumatic tire with a tire size of 235 / 35R19 to a rim with a rim size of 19 × 8 1 / 2J, and an air pressure of 230 [kPa]. And the maximum load specified by JATMA. The pneumatic tire is mounted on a front engine rear drive (FR) vehicle having a displacement of 3.0 [L] as a test vehicle. Then, the test vehicle travels on a circuit of 2 km per lap that is a dry road surface, and the evaluation panel performs sensory evaluation by a five-point method. This evaluation is preferable as the numerical value increases.

  (3) The durability performance was evaluated by a low-pressure durability test using an indoor drum tester. A pneumatic tire with a tire size of 235 / 35R19 was assembled to a rim with a rim size of 19 × 8 1 / 2J. The air pressure is 250 [kPa] and the load is 5.3 [kN]. Then, the load is gradually increased, and the running time until the load reaches 270 [%] or the tire breaks is measured. And 5-point evaluation is performed based on this measurement result. This evaluation is preferable as the numerical value increases.

  The pneumatic tire 1 of Examples 1 to 16 has the configuration described in FIGS. 1 to 3, and the three-dimensional sipe 21 in which the rim protect bar 2 extends in a zigzag shape in the sipe depth direction and the tire circumferential direction. Have The distance D1 from the opening of the three-dimensional sipe 21 to the inner peripheral surface of the sidewall rubber 16 constituting the rim protect bar 2 is D1 = 7.5 [mm].

  In the conventional pneumatic tire, the rim protect bar 2 does not have the three-dimensional sipe 21 in the configuration of FIG. In the pneumatic tire of the comparative example, in the configuration of FIG. 1, the rim protect bar 2 has a straight circumferential groove extending in the tire circumferential direction instead of the three-dimensional sipe 21.

  As shown in the test results, it can be seen that, in the pneumatic tires 1 of Examples 1 to 16, the riding comfort performance of the tire is improved, and the steering stability performance and the durability performance of the tire are ensured.

  1 Pneumatic tire, 2 rim protect bar, 21 3D sipe, 11 bead core, 12 bead filler, 13 carcass layer, 14 belt layer, 141, 142 cross belt, 15 tread rubber, 16 sidewall rubber, 17 rim cushion rubber, 18 Inner liner

Claims (9)

A pair of left and right bead cores, a carcass layer spanned between the left and right bead cores, a belt layer disposed on the outer side in the tire radial direction of the carcass layer, a tread rubber constituting a tread portion, and a sidewall portion are configured. A pneumatic tire comprising left and right sidewall rubbers, left and right rim cushion rubbers constituting a bead portion, an inner liner disposed on an inner peripheral surface of the tire, and a rim protect bar disposed on the sidewall portion. And
The pneumatic tire is characterized in that the rim protect bar has a three-dimensional sipe extending in the tire circumferential direction. In a sectional view in the tire meridian direction, the maximum height position of the rim protect bar with respect to the inner peripheral surface of the sidewall rubber constituting the rim protect bar is referred to as a vertex P, and from the vertex P, the inner liner When the perpendicular drawn to the inner peripheral line is called a reference line S,
The pneumatic tire according to claim 1, wherein the three-dimensional sipe has a zigzag shape or a wavy shape extending inward in the tire width direction along a reference line S of the rim protect bar.   The pneumatic according to claim 2, wherein the distance between the opening of the three-dimensional sipe and the reference line S of the rim protect bar is in a range of 2.0 [mm] or less in a cross-sectional view in the tire meridian direction. tire.   The pneumatic tire according to any one of claims 1 to 3, wherein the three-dimensional sipe has a zigzag shape or a wavy shape extending in a tire circumferential direction.   The pneumatic tire according to claim 4, wherein a wavelength L of the three-dimensional sipe with respect to a tire circumferential direction is in a range of 2.0 [mm] ≦ L ≦ 4.0 [mm].   The pneumatic tire according to claim 4 or 5, wherein a bending width B of the three-dimensional sipe with respect to a tire circumferential direction is in a range of 0.5 [mm] ≤ B ≤ 4.0 [mm].   The pneumatic according to any one of claims 1 to 5, wherein a bending width A of the three-dimensional sipe with respect to a sipe depth direction is in a range of 0.5 [mm] ≤ A ≤ 4.0 [mm]. tire.   A distance D1 from the opening of the three-dimensional sipe to the inner peripheral surface of the sidewall rubber constituting the rim protect bar, and the bottom of the three-dimensional sipe constitute the rim protect bar in a cross-sectional view in the tire meridian direction The distance D2 to the inner peripheral surface of the sidewall rubber to be sipe and the sipe depth D3 of the three-dimensional sipe have a relationship of 1.5 [mm] ≦ D2 and 0.6 ≦ D3 / D1. The pneumatic tire according to any one of 7 above.   The pneumatic tire according to claim 1, wherein a sipe width W of the three-dimensional sipe is in a range of 0.1 [mm] ≦ W ≦ 1.0 [mm].