tire

Abstract

To provide a tire with superior braking performance on icy and snowy roads. [Solution] The tire 10 is provided with sipes 24 on the tread surface 12. The sipes 24 have a sipe body 30 and a water channel 32. The sipe body 30 has an opening 31 on the tread surface 12 and has a longitudinal length L, a widthwise length C2, and a tire radial length H1. The water channel 32 has an inlet 34 that extends along the longitudinal direction of the sipe body 30 and connects to the inner surface 32S of the water channel 32, and a small groove 36 that extends longitudinally and is provided on the inner surface 32S. The longitudinal end 26 of the water channel 32 is in communication with the tire surface, and the widthwise length of the water channel 32 is greater than the widthwise length of the sipe body 30.

Description

Technical Field

[0001] The present invention relates to a tire.

Background Art

[0002] As a tire suitable for driving on an icy or snowy road surface, a tire has been disclosed which improves braking performance on ice by increasing the water absorption speed in the sipe. For example, Patent Document 1 discloses a tire tread having a tread surface adapted to contact the road surface when the tire rolls, the tire tread including a plurality of cuts opening on the tread surface, each cut having a sipe delimited by opposing first walls and a widened portion defined by a second wall widening the sipe at the depth of the tread, the roughness of the first wall being different from the roughness of the second wall.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] On an icy or snowy road surface, a tire that exhibits more excellent braking performance is desired.

[0005] An object of the present invention is to provide a tire having more excellent braking performance on an icy or snowy road surface.

Means for Solving the Problems

[0006] The tire of the present invention is a tire provided with sipes on the tread surface, wherein the sipe has a sipe body and a water guide channel, the sipe body has an opening on the tread surface and has a longitudinal length, a widthwise length, and a tire diameter direction length, The water conduit has an inlet that extends along the longitudinal direction of the sipe body and connects to the inner surface of the water conduit, and a small groove that extends along the longitudinal direction and is provided on the inner surface. The aforementioned inlet is in communication with the sipe body, One end of the aforementioned water channel in the longitudinal direction is in communication with the tire surface. The widthwise length of the water conduit is greater than the widthwise length of the sipe body. [Effects of the Invention]

[0007] The tire of the present invention offers superior braking performance on icy and snowy road surfaces. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows a portion of the tire in the width direction relative to the tire's equatorial plane, viewed from a meridional cross-section of the tire according to this embodiment. [Figure 2] This is a partial cross-sectional view along line II-II in Figure 1. [Figure 3] This is a partially enlarged view along the line III-III in Figure 2. [Figure 4] This is a partial cross-sectional view along line IV-IV in Figure 2. [Figure 5] Figure 5A is a partially enlarged view corresponding to Figure 3, showing a modified example of the sipe according to this embodiment, with Figure 5A being Modification 1, Figure 5B being Modification 2, Figure 5C being Modification 3, and Figure 5D being Modification 4. [Modes for carrying out the invention]

[0009] The tire of the present invention relates to the following embodiments.

[0010] [Aspect 1] A tire having sipes on the tread surface, The sipe comprises a sipe body and a water channel. The sipe body has an opening on the tread surface and has a longitudinal length, a widthwise length, and a tire radial length. The water guiding channel extends along the longitudinal direction of the sipe body and has an inlet connected to the inner surface of the water guiding channel and a longitudinally extending small groove provided on the inner surface. The inlet communicates with the sipe body. One end in the longitudinal direction of the water guiding channel communicates with the tire surface. The tire, wherein the widthwise length of the water guiding channel is greater than the widthwise length of the sipe body.

[0011] [Aspect 2] The tire according to Aspect 1, wherein one end of the sipe communicates with the tire side surface outside the tire width direction from the grounding end.

[0012] [Aspect 3] The tire according to Aspect 1 or 2, wherein the small groove is arranged in a spiral shape with respect to the longitudinal direction of the water guiding channel.

[0013] [Aspect 4] The tire according to any one of Aspects 1 to 3, wherein the maximum width length of the small groove is 0.1 mm or more and 0.8 mm or less.

[0014] [Aspect 5] The tire according to any one of Aspects 1 to 4, wherein the maximum depth of the small groove is 0.1 mm or more and 0.5 mm or less.

[0015] [Aspect 6] The tire according to any one of Aspects 1 to 5, wherein the maximum tire radial length of the sipe is 2.0 mm or more and 10.0 mm or less.

[0016] [Aspect 7] The tire according to any one of Aspects 1 to 6, wherein the widthwise length of the sipe body is 0.1 mm or more and 1.0 mm or less.

[0017] [Aspect 8] In a cross-section intersecting the longitudinal direction of the sipe, the cross-sectional area ratio A / B of the cross-sectional area A of the water guiding channel and the cross-sectional area B of the sipe body is 0.5 or more and 1.0 or less. The tire according to any one of Aspects 1 to 7.

[0018] (Tire configuration) Embodiments of the present invention will be described below with reference to the drawings. In the following description, the tire radial direction refers to the direction perpendicular to the tire rotation axis, the inner side of the tire radial direction refers to the side toward the tire rotation axis in the tire radial direction, and the outer side of the tire radial direction refers to the side away from the tire rotation axis in the tire radial direction. The tire circumferential direction refers to the direction around the tire rotation axis as the central axis. Furthermore, the tire width direction refers to the direction parallel to the tire rotation axis, the inner side of the tire width direction refers to the side toward the tire equatorial plane (tire equator line) in the tire width direction, and the outer side of the tire width direction refers to the side away from the tire equatorial plane in the tire width direction. The tire equatorial plane is a plane perpendicular to the tire rotation axis and passing through the center of the tire width of the tire. "Along with" a certain standard includes along directions within a range of less than ±45° with respect to a certain standard.

[0019] Similarly, in the following explanation, "regular rim" refers to the "applicable rim" as defined by JATMA, the "Design Rim" as defined by TRA, or the "Measuring Rim" as defined by ETRTO.

[0020] Similarly, in the following explanation, "normal internal pressure" refers to the "maximum air pressure" specified by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "INFLATION PRESSURES" specified by ETRTO. Furthermore, "normal load" refers to the "maximum load capacity" specified by JATMA, the maximum value listed in "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" specified by TRA, or "LOAD CAPACITY" specified by ETRTO.

[0021] Figure 1 shows a meridional cross-sectional view of the tire 10 according to this embodiment, showing one side in the tire width direction relative to the tire equatorial plane CP. Note that the figure shows the tire portion in a state where it is mounted on a rim, subjected to normal internal pressure, and under no load.

[0022] The tire 10 has a tread surface 12 and a tire sidewall 14. The tread surface 12 is made of rubber material (tread rubber). The tread surface 12 comes into contact with the road surface when the vehicle is running. The tread surface 12 is annular, has a predetermined length in the tire width direction, and is continuous in the tire circumferential direction. The tread surface 12 has a circumferential main groove 16 extending along the tire circumferential direction, and a land area 18 partitioned by the circumferential main groove. On the tread surface 12, with the circumferential main groove 16 located on the outermost side in the tire width direction as the reference, the land area 18 formed inward from the circumferential main groove 16 in the tire width direction is called the center land area 20, and the land area 18 formed outward from the circumferential main groove 16 in the tire width direction is called the shoulder land area 22. The shoulder land area 22 has sipes 24.

[0023] The sipes 24 extend along the tire width direction. The outer end 26 of the sipes 24 in the tire width direction communicates with the tire sidewall 14 outside the contact end E in the tire width direction. The inner end 28 of the sipes 24 in the tire width direction terminates within the shoulder land portion 22.

[0024] The contact end E is the maximum position in the tire width direction at the contact surface between the tire 10 and the flat plate when the tire 10 is mounted on a regular rim, subjected to regular internal pressure, and placed perpendicular to the flat plate in a stationary state, with a load corresponding to a regular load (80% of the maximum load capacity) applied.

[0025] The sipe 24 has a sipe body 30 and a water channel 32. The sipe body 30 is a groove with an opening 31 in the tread surface 12. The sipe body 30 has a longitudinal length L, a widthwise length D1, and a tire radial length H1. The sipe body 30 is arranged so that its longitudinal direction is aligned with the tire width direction. The water channel 32 is arranged along the sipe body 30. The water channel 32 has a widthwise length D2 that is greater than the widthwise length D1 of the sipe body 30. In the tire radial direction, the widthwise length of the sipe body 30 can change within a range of ±5%. That is, the boundary between the sipe body 30 and the water channel 32 may be the position where the widthwise length changes by 5% or more. For example, the range in which the change in widthwise length is less than 5% of the widthwise length at the opening 31 of the sipe body 30 may be defined as the sipe body 30, and the range in which the change in widthwise length is 5% or more of the widthwise length at the opening 31 may be defined as the water channel 32.

[0026] Figure 2 is a partial cross-sectional view along line II-II in Figure 1, that is, a partial cross-sectional view at the point where the radial length of the sipe 24 in the tire direction is maximum. The widthwise length D1 of the sipe body 30 is preferably 0.1 mm or more and 1.0 mm or less, 0.3 mm or more and 0.8 mm or less, or 0.45 mm or more and 0.65 mm or less. The widthwise length D1 of the sipe body 30 may also be the average value of the widthwise lengths measured at three different locations in the radial direction of the tire.

[0027] The water conduit 32 is a flow channel having an internal space that extends in the longitudinal direction. The water conduit 32 has an inlet 34. The inlet 34 extends along the longitudinal direction of the water conduit 32 and connects to the internal space. The inlet 34 of the water conduit 32 communicates with the sipe body 30. The water conduit 32 shown in Figure 2 is located at the bottom of the sipe body 30 and is a cylindrical flow channel with an inlet 34 at its upper end and an inner diameter larger than the widthwise length of the sipe body 30 in a cross-sectional view. The inlet 34 of the water conduit 32 communicates with the bottom of the sipe body 30. In Figure 2, the midpoint C1 in the widthwise direction of the sipe body 30 and the center C2 of the water conduit 32 are located at positions that overlap in the tire radial direction. The inlet 34 is provided at the outermost part of the water conduit 32 in the tire radial direction, and this inlet 34 communicates with the innermost part in the tire radial direction, which is the bottom of the sipe body 30. The water conduit 32 has a plurality of small grooves 36 on its inner surface 32S that is exposed to the internal space. The small grooves 36 extend along the longitudinal direction of the water conduit 32. The inner diameter of the water conduit 32 is preferably 0.15 mm to 2.0 mm, 0.4 mm to 1.6 mm, or 0.6 mm to 1.3 mm. The inner diameter of the water conduit 32 is based on the inner surface 32S.

[0028] As shown in Figure 3, the water conduit 32 has six small grooves 36. Each small groove 36 is rectangular in shape, having a pair of side surfaces 38 and a bottom surface 40 positioned between the side surfaces 38 in cross-sectional view. Each small groove 36 has a depth D3 and a width length W. The depth D3 of the small groove 36 is the length from the inner surface 32S of the water conduit 32 to the bottom surface 40 of the small groove 36. The maximum depth D3 of the small groove 36 is preferably 0.1 mm or more and 0.5 mm or less, or 0.2 mm or more and 0.4 mm or less. The depth D3 of the small groove 36 is the maximum value obtained by measuring the length between the inner surface 32S of the water conduit 32 and the bottom surface 40 of the small groove 36 at which a perpendicular L1 drawn from the inner surface 32S of the water conduit 32 intersects.

[0029] The width length W of the small groove 36 is the length between the sides 38 of the small groove 36. The maximum width length W of the small groove 36 is preferably 0.1 mm or more and 0.8 mm or less, or 0.3 mm or more and 0.6 mm or less. The width length W of the small groove 36 is the maximum value obtained by measuring the length between the sides 38 that intersect with a virtual line L2 perpendicular to the longitudinal direction and depth direction of the small groove 36.

[0030] The small groove 36 is demarcated by a protrusion 42. The protrusion 42 is rectangular in shape, having a pair of side surfaces and a top surface positioned between the side surfaces in a cross-sectional view. The side surfaces of the protrusion 42 are the side surfaces 38 of the small groove 36. The top surface of the protrusion 42 is the inner surface 32S of the water conduit 32.

[0031] The maximum depth H of the sipe 24 (Figure 1) is the total length in the tire radial direction at the position where the sum of the tire radial length H1 of the sipe body 30 and the tire radial length H2 of the water conduit 32 is greatest. The maximum depth H of the sipe 24 is preferably 2.0 mm to 10.0 mm, 4.0 mm to 8.0 mm, or 5.0 mm to 7.0 mm. The maximum depth H of the sipe 24 is the value obtained by measuring the length in the tire radial direction from the tread surface 12 to the innermost position in the tire radial direction of the water conduit 32 including the small groove 36.

[0032] Cross-sectional area A of water conduit 32 (mm²) 2 ) and the cross-sectional area B (mm²) of the sipe body 30. 2The cross-sectional area ratio A / B of the sipe body 32 is preferably 0.5 to 1.0 or 0.6 to 0.9. Cross-sectional areas A and B are both the cross-sectional areas at the position where the sum of the lengths of the sipe body 30 and the water conduit 32 in the tire radial direction is largest. Cross-sectional area A of the water conduit 32 is the area inward from the inlet 34 in the tire radial direction and includes the cross-sectional area of ​​the small groove 36. Cross-sectional area B of the sipe body 30 is the cross-sectional area in the range from the opening 31 to the inlet 34. The larger the cross-sectional area A of the water conduit 32 is compared to the cross-sectional area B of the sipe body 30, the larger the cross-sectional area ratio A / B becomes, and the larger the amount of water that can be discharged from the water conduit 32, but the lower the block rigidity. The smaller the cross-sectional area A of the water conduit 32 is compared to the cross-sectional area B of the sipe body 30, the smaller the cross-sectional area ratio A / B becomes, and the amount of water discharged from the water conduit 32 decreases compared to the amount of water taken into the sipe body 30.

[0033] As shown in Figure 3, the sipe 24 has a concave portion 46 at the connection point between the sipe body 30 and the water conduit 32, i.e., at the inlet 34 of the water conduit 32. The concave portion 46 has a shape in which the inner surface 32S of the water conduit 32 is recessed outward from the water conduit 32 and extends along the longitudinal direction of the water conduit 32. The concave portions 46 shown in Figure 3 are provided on both sides of the bottom (inlet 34) with respect to the center in the width direction of the sipe body 30.

[0034] The small groove 36 may be inclined with respect to the longitudinal direction of the water conduit 32. As shown in Figure 4, the small groove 36 is spiral. The small groove 32 may be clockwise or counterclockwise when viewed from the end 26. The rotation angle of the small groove 32 from end 26 to end 28 may be 360° or less. The angle α between the direction of extension of the small groove 36 and the longitudinal direction of the water conduit 32 may be 1° to 10° or 4° to 8°.

[0035] The angle α can be measured as follows. First, the shoulder land portion 22 including the water conduit is cut out from the tire 10. The range of the shoulder land portion 22 cut out from the tire 10 in the tire width direction includes the inner end 28 of the sipe 24 in the tire width direction and the tread end E. Next, the water conduit 32 is cut along the ZZ line shown in Figure 2 to divide it into two parts: a part including the sipe body 30 and a part including the semicircular water conduit 32 in cross-sectional view. Next, the part including the semicircular water conduit 32 in cross-sectional view is taken as a sample, and the sample is observed with a microscope from the outside in the tire radial direction to set a virtual center line of the water conduit 32. The virtual center line is a line that passes through the middle of the width length of the water conduit in the sample and follows the longitudinal direction of the water conduit. Next, the angle α between the virtual center line and the small groove 32 is measured.

[0036] The tire of this embodiment, although not shown in its entirety, has a meridional cross-sectional shape similar to that of a conventional pneumatic tire. That is, in a meridional cross-sectional view of the tire, the tire of this embodiment has a bead portion, a sidewall portion, a shoulder portion, and a tread portion, extending from the inside to the outside in the radial direction of the tire. Furthermore, the tire has, for example, in a meridional cross-sectional view of the tire, a carcass layer that extends from the tread portion to the bead portions on both sides and is wound around a pair of bead cores, and a belt layer and, optionally, a belt cover layer are provided on the radially outer side of the carcass layer.

[0037] The tire of this embodiment described above is obtained through the usual manufacturing processes, namely the mixing process of tire materials, the processing process of tire materials, the molding process of the green tire, the vulcanization process, and the inspection process after vulcanization. When manufacturing the tire of this embodiment, protrusions and recesses corresponding to a predetermined tread pattern are formed on the inner wall of the vulcanization mold, and vulcanization is performed using this mold.

[0038] (Mechanism of Action and Effects) Next, the operation and effects of the tire 10 configured as described above will be explained. When the tire 10 is driving on an icy or snowy road surface, water from the icy or snowy road surface comes into contact with the tread surface 12. The sipes 24 formed on the tread surface 12 take in water from the icy or snowy road surface through the openings 31 of the sipe body 30. The water taken in by the sipe body 30 moves inside the sipe body 30 in the tire diameter direction and reaches the water conduit 32. The water that reaches the water conduit 32 moves inside the water conduit 32 in the tire width direction and is discharged to the outside of the tire 10 from the tire sidewall 14.

[0039] The water conduit 32 has small grooves 36 on its inner surface 32S, causing water in the conduit 32 to flow along the small grooves 36. As the water in the conduit 32 flows along the small grooves 36, it tends to become laminar. When water in the conduit 32 becomes laminar, its flow velocity increases, making it easier to flow along the conduit 32. Therefore, the tire 10 can smoothly discharge the water that has moved from the sipe body 30 into the conduit 32 to the outside of the tire 10.

[0040] In this way, the tire 10 guides the water taken in from the tread surface 12 to the sipes 24 into the water conduit 32 and smoothly discharges it from the water conduit 32 in the tire width direction, thereby continuously taking in water from the tread surface 12 to the sipes 24 while driving on icy and snowy roads and wet roads. Therefore, the tire 10 has excellent braking performance on icy and snowy roads, i.e., excellent braking performance on ice and wet surfaces.

[0041] Because the outer end 26 of the sipe 24 in the tire width direction is in communication with the tire sidewall 14 that is outside the contact end E in the tire width direction, some of the water taken into the sipe body 30 can move outward in the tire width direction within the sipe body 30 and be directly discharged outward from the tire sidewall 14 in the tire width direction. Therefore, the tire 10 can efficiently discharge the water taken into the sipe 24 from the tread surface 12 outward in the tire width direction. Consequently, the tire 10 has superior braking performance on icy and snowy roads.

[0042] Because the small grooves 36 are arranged spirally in the longitudinal direction of the water conduit 32, the water in the water conduit 32 becomes laminar more easily, and thus the flow velocity increases more easily. Therefore, the tire 10 can more smoothly discharge the water that has moved from the sipe body 30 into the water conduit 32 to the outside of the tire 10. Consequently, the tire 10 has excellent braking performance on ice.

[0043] The maximum width and length W of the small groove 36 is 0.1 mm to 0.8 mm, which allows water in the water conduit 32 to flow easily along the small groove 36. The maximum depth D3 of the small groove 36 is 0.1 mm to 0.5 mm, which also allows water in the water conduit 32 to flow easily along the small groove 36. Therefore, the tire 10 can smoothly discharge water taken in from the opening 31 through the sipe body 30 into the water conduit 32, resulting in superior braking performance on ice.

[0044] The maximum radial length H of the sipe 24 is between 2.0 mm and 10.0 mm, which ensures the volume of the sipe body 30 and suppresses a decrease in block rigidity. When the length H of the sipe 24 is below the above upper limit, the decrease in block rigidity is suppressed, preventing the block from collapsing excessively. This suppresses a decrease in the contact area, resulting in excellent braking performance on ice. When the length H of the sipe 24 is above the above lower limit, excellent block rigidity is obtained, and the block deforms appropriately, allowing the edges of the sipe 24 to make more reliable contact with the road surface. This results in excellent braking performance on ice. Therefore, the tire 10 is superior in ice braking performance while suppressing a decrease in wear resistance.

[0045] The sipe body 30, with a widthwise length D1 of 0.1 mm or more and 1.0 mm or less, more reliably exhibits capillary action, allowing water taken in from the tread surface 12 to be more reliably moved to the water conduit 32. Therefore, the tire 10 has superior braking performance on ice.

[0046] In the cross-sections intersecting the longitudinal direction of the sipes 24, the ratio of the cross-sectional area A of the water conduit 32 to the cross-sectional area B of the sipe body 30, A / B, is between 0.5 and 1.0. This allows the tire 10 to more reliably discharge water taken in from the tread surface 12 through the water conduit 32 while suppressing a decrease in block rigidity. Therefore, the tire 10 can maintain superior braking performance on icy and snowy road surfaces.

[0047] The sipe 24 has a concave portion 46 at the connection point between the sipe body 30 and the water conduit 32, which allows water to flow more smoothly from the sipe body 30 to the water conduit 32. In addition, by providing the concave portion 46 at the connection point between the sipe body 30 and the water conduit 32, the blades forming the sipe 24 can be easily removed from the vulcanized tire 10 during manufacturing, thereby preventing damage to the connection point.

[0048] Furthermore, the tire 10 of this embodiment described above can be either a pneumatic tire or an airless tire. In other words, any tire having the features shown as an example in Figure 1 is included within the scope of the present invention.

[0049] (modified version) The present invention is not limited to the embodiments described above, and can be modified as appropriate within the scope of the spirit of the invention.

[0050] For example, in the above embodiment, the case described is one in which the outer end 26 of the sipe 24 in the tire width direction communicates with the tire side surface 14 that is outside the tire width direction from the contact end E, but the present invention is not limited to this. For example, the sipe 24 may communicate with the tread surface 12 that is inside the tire width direction from the tire contact end E. Also, the sipe 24 may have a water channel 32 that communicates with the tire side surface 14 that is outside the tire width direction from the contact end E, but the sipe body 30 does not have to communicate with the tire side surface 14 that is outside the tire width direction from the contact end E.

[0051] In the above embodiment, the case in which the inlet 34 of the water conduit 32 communicates with the bottom of the sipe body 30 was described, but the present invention is not limited to this. For example, the water conduit 32 may be located within the range from the opening 31 exposed on the tread surface 12 of the sipe body 30 to the bottom 34. That is, the inlet 34 of the water conduit 32 may communicate with the side wall of the sipe body 30. Also, although the case in which one water conduit 32 is located on the sipe body 30 was described, two or more water conduits may be located on the sipe body 30. Furthermore, although the shape of the water conduit 32 as viewed from the tire width direction (shape excluding the small groove 36) was described as cylindrical, it may also be polygonal or elliptical.

[0052] In the above embodiment, the center C2 of the water conduit 32 was described as being positioned to coincide with the midpoint C1 in the width direction of the sipe body 30 in the tire diameter direction, but the present invention is not limited to this. For example, it is sufficient for the water conduit 32 to communicate with the sipe body 30 in part, and the center C2 of the water conduit 32 may be offset in the width direction of the sipe body 30 from the midpoint C1 in the width direction of the sipe body 30.

[0053] In the above embodiment, the water conduit 32 was described as having six small grooves 36, but the present invention is not limited to this, and may have one or more. The case in which the small grooves 36 are rectangular when viewed from the longitudinal direction of the water conduit 32 was described, but the present invention is not limited to this. For example, as shown in Figure 5, the small grooves 36 can take on various shapes when viewed from the longitudinal direction of the water conduit 32. The water conduit 32A in Figure 5A has trapezoidal small grooves 36A when viewed from the longitudinal direction of the water conduit 32A. The water conduit 32A has mountain-shaped protrusions 42A arranged between the small grooves 36A. The water conduit 32B in Figure 5B has substantially rectangular small grooves 36B when viewed from the longitudinal direction of the water conduit 32B. The water conduit 32B has semi-cylindrical protrusions 42B arranged between the small grooves 36B. The water conduit 32C in Figure 5C has triangular small grooves 36C when viewed from the longitudinal direction of the water conduit 32C. The water conduit 32C has triangular protrusions 42C between the small grooves 36C that correspond to the shape of the inverted small grooves 36C. The water conduit 32D in Figure 5D has isosceles triangular small grooves 36D when viewed from the longitudinal direction of the water conduit 32D. The water conduit 32D has isosceles triangular protrusions 42D between the small grooves 36D that correspond to the shape of the inverted small grooves 36D. The water conduits 32A, 32B, 32C, and 32D in Figures 5A, 5B, 5C, and 5D have small grooves 36A, 36B, 36C, and 36D respectively, and thus exhibit the same effects as the above embodiment.

[0054] In Figures 5A, 5B, 5C, and 5D, the water channels 32A, 32B, 32C, and 32D each have a concave portion 46 at the connection point between the sipe body 30 and the water channels 32A, 32B, 32C, and 32D. This allows water to flow more smoothly from the sipe body 30 to the water channels 32A, 32B, 32C, and 32D compared to a direct connection from the sipe body 30 to the inner surface of the water channels 32A, 32B, 32C, and 32D.

[0055] In the above embodiment, the sipe 24 was described as having a concave portion 46 at the connection point between the sipe body 30 and the water conduit 32, but the present invention is not limited to this. If there is no concave portion 46 between the bottom of the sipe body 30 (inlet 34 of the water conduit 32) and the inner surface 32S of the water conduit 32, edges may be formed on both sides of the bottom (inlet 34) in the width direction. It is preferable that these edges be removed by chamfering. [Examples]

[0056] Tires according to Examples 1 to 9, and a pneumatic tire according to the Reference Example, were manufactured with a tire size of 205 / 55R16 91H (as defined by JATMA), and equipped with sipe bodies and sipes having water conduits in the shape shown in Figure 1 when mounted on a rim. The detailed specifications of these tires are shown in Table 1 below.

[0057] In Table 1, the average extension angle of the small grooves, the width W of the small grooves, the depth D3 of the small grooves, the sipe depth H, and the sipe width D1 all conform to the descriptions provided in this specification. In Table 1, "Presence or Absence of Small Grooves" indicates that the water channel has small grooves (6 in total). "Absence" indicates that the sipe includes a water channel but does not have small grooves. In the "Presence or Absence of Communication" column, "Presence" indicates that the sipe body communicates with the tire sidewall on the outside in the tire width direction from the contact end, while "Absence" indicates that there is no communication. In the "Shape of Small Grooves" column, "Inclined" indicates that the small groove is spiral inclined with respect to the longitudinal direction of the water channel. In this case, the extension angle of the small groove was 4°. "Parallel" indicates that the small groove is parallel to the longitudinal direction of the water channel.

[0058] The tires produced in this manner according to Examples 1 to 9, as well as the reference example tire, were mounted on 16 x 6.5J aluminum rims at 230 kPa. Each test tire was then mounted on a front-wheel-drive test vehicle (engine displacement: 1500cc), and the ice braking performance, wet braking performance, and resistance to uneven wear were evaluated according to the following procedure.

[0059] (Ice braking performance) Under load conditions equivalent to two passengers, the test vehicle was subjected to ABS braking at a speed of 20 km / h on an icy test course. The braking distance was measured, and the reciprocal of the measured value was calculated. Based on this calculation, an index evaluation was performed with the conventional example as the baseline (100). The evaluation results are shown in Table 1. In this evaluation, a higher index indicates better braking performance on ice.

[0060] (Wet braking performance) A test course with a flat, wet surface was used, and test vehicles were driven from 180 km / h until a complete stop using a decelerating vehicle. The reciprocal of the distance traveled was calculated. Wet braking performance is expressed on a scale where the conventional example is rated at 100, with a higher number indicating better performance. The results are shown in Table 1.

[0061] (Abrasion resistance) For the test vehicle, the difference in wear on each part of the vehicle (heel-and-toe wear) was measured after 10,000 km of pattern driving, and the reciprocal of the measured value was calculated. Based on this calculation result, an index evaluation was performed with the conventional example as the baseline (100). The evaluation results are shown in Table 1. In this evaluation, a higher index indicates superior wear resistance.

[0062] [Table 1]

[0063] According to Table 1, it was confirmed that the tires of Examples 1 to 9, which fall within the technical scope of the present invention, all exhibit superior ice braking performance and wet braking performance compared to the reference example tire, which does not fall within the technical scope of the present invention. Compared to Example 1, Example 2 showed improved ice braking performance and wet braking performance because the sipe body communicates with the tire sidewall on the outer side in the tire width direction from the contact end. Compared to Example 2, Example 3 showed improved ice braking performance because the small grooves are spiral-shaped. Compared to Example 3, Example 4 showed improved ice braking performance because the width of the small grooves is 0.3 mm. Compared to Example 4, Example 5 showed improved ice braking performance because the depth of the small grooves is 0.3 mm. Compared to Example 5, Example 6 showed improved ice performance and wear resistance because the sipe depth is 7 mm. Compared to Example 6, Example 7 showed improved ice braking performance because the widthwise length D1 of the sipe body is 0.4 mm. In Example 8, the cross-sectional area ratio of the water conduit to the sipe body was 0.7, resulting in improved wear resistance compared to Example 7. In Example 9, the cross-sectional area ratio A / B was 1.5, which reduced block rigidity and consequently lowered wear resistance. However, this does not pose a practical problem and is within an acceptable range. [Explanation of Symbols]

[0064] 10 tires 12 Tread surface 14 Tire side 16 Circumferential main groove 18 Land Department 20 Center Track and Field Club 22 Shoulder Track and Field Club 24 sipes 26. Outer edge (sipe) in the width direction of the tire 28 End (sipe) 30 Sipe Body 31 Aperture 32 Water conduit 34 Entrance 36 Small ditch 38 Side view 40 Bottom 42 Convex part 46 Concave part E Ground end D1 Sipe body width D2 Width of the water conduit D3 Depth of small groove H Sipe Depth H1 Sipe body length in the tire radial direction H2 Diameter of the water conduit L Sipe Body Length in the Longitudinal Direction L1 Perpendicular line L2 virtual line C1 Midpoint in the width direction of the sipe body Center of the C2 water conduit W width of the small groove

Claims

1. A tire having sipes on the tread surface, The sipe comprises a sipe body and a water channel. The sipe body has an opening on the tread surface and has a longitudinal length, a widthwise length, and a tire radial length. The water conduit has an inlet that extends along the longitudinal direction of the sipe body and connects to the inner surface of the water conduit, and a small groove that extends along the longitudinal direction and is provided on the inner surface. One end of the aforementioned water channel in the longitudinal direction is in communication with the tire surface. A tire in which the widthwise length of the water conduit is greater than the widthwise length of the sipe body.

2. The tire according to claim 1, wherein one end of the sipe communicates with the tire side surface on the tire width direction outward from the contact end.

3. The tire according to claim 1, wherein the small grooves are arranged spirally with respect to the longitudinal direction of the water conduit.

4. The tire according to claim 1, wherein the maximum width and length of the small groove is 0.1 mm or more and 0.8 mm or less.

5. The tire according to claim 1, wherein the maximum depth of the small groove is 0.1 mm or more and 0.5 mm or less.

6. The tire according to claim 1, wherein the maximum radial length of the sipe is 2.0 mm or more and 10.0 mm or less.

7. The tire according to claim 1, wherein the widthwise length of the sipe body is 0.1 mm or more and 1.0 mm or less.

8. The tire according to claim 1, wherein in a cross-section intersecting the longitudinal direction of the sipe, the ratio of the cross-sectional area A of the water channel to the cross-sectional area B of the sipe body, A / B, is 0.5 or more and 1.0 or less.

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