JP2010234897A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely prevent the occurrence of cracks in a rubber block formed on a tread when a reinforcement rubber layer is provided on a surface of the tread. <P>SOLUTION: The pneumatic tire 1 includes a carcass layer 12, an inner liner 13, and a pair of beads 14. A belt layer 15 is provided on the tire radial outer side of the carcass layer 12. A tread 16 grounded on a road surface is provided on the tire radial outer side of the belt layer 15. The tread 16 includes a tread rubber layer 16a, and the reinforcement rubber layer 16b. The reinforcement rubber layer 16b is disposed on the tire radial outer side of the tread rubber layer 16a. The reinforcement rubber layer 16b includes a short fiber 101. At least part of the short fiber 101 is orientated in a peripheral direction of the pneumatic tire 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a pneumatic tire including a rubber block formed on a tread and a reinforcing rubber layer that covers the surface of the tread and reinforces the rubber block.

  Conventionally, in pneumatic tires that are mounted on automobiles, especially heavy-duty pneumatic tires that are mounted on trucks and are heavily loaded, the rubber block formed on the tread that contacts the road surface deforms along the tread width direction. There is a problem that cracks due to the wiping phenomenon occur easily.

  In order to prevent the occurrence of such cracks, a method of providing a reinforcing rubber layer containing short fibers on the surface of the tread is known (for example, Patent Document 1).

JP 61-119409 (page 6, FIG. 1)

  By the way, in recent years, an automobile using an electric motor and a fuel cell has been put into practical use instead of an automobile using an internal combustion engine. An automobile in which an electric motor is used as a power source has a feature that a driving torque, particularly a driving torque at a low rotation speed is very large as compared with an automobile using an internal combustion engine.

  In such a pneumatic tire mounted on an automobile, a burden on the rubber block at the time of starting or accelerating becomes extremely large. For this reason, even if the above-described conventional reinforcing rubber layer is used, there is a concern that the amount of shear deformation of the rubber block is large and the occurrence of cracks in the rubber block cannot be sufficiently prevented.

  Therefore, the present invention has been made in view of such a situation, and in the case where a reinforcing rubber layer is provided on the surface of the tread, air that can more reliably prevent the occurrence of cracks in the rubber block formed on the tread. An object is to provide a tire entering.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a tread (tread portion 16) that contacts the road surface, a rubber block (rubber block 17) formed on the tread, and a surface of the tread are covered to reinforce the rubber block. A pneumatic tire (pneumatic tire 1) including a reinforcing rubber layer (reinforcing rubber layer 16b), wherein the reinforcing rubber layer includes short fibers (short fibers 101), and at least a part of the short fibers The gist is that it is oriented along the circumferential direction of the pneumatic tire.

  According to the first feature of the present invention, the short fibers contained in the reinforcing rubber layer are oriented along the circumferential direction of the pneumatic tire. Thereby, the deformation | transformation of the circumferential direction of the pneumatic tire of a rubber block is suppressed. For this reason, the shear rigidity along the circumferential direction of the pneumatic tire when a large driving force is applied to the pneumatic tire can be increased.

  When such a pneumatic tire is mounted on, for example, an automobile using an electric motor as a driving source, even if a large driving force is applied to the rubber block at the time of start and acceleration, the shear deformation amount of the rubber block is reduced. be able to.

  Therefore, according to the 1st characteristic of this invention, generation | occurrence | production of the crack in the rubber block formed in the tread can be prevented reliably.

  A second feature of the present invention relates to the first feature of the present invention, wherein the reinforcing rubber layer includes an inner reinforcing rubber layer (inner reinforcing rubber layer 161) and the pneumatic tire (more than the inner reinforcing rubber layer). An outer reinforcing rubber layer (outer reinforcing rubber layer 162) provided on the radially outer side of the pneumatic tire 2), and the short fibers (short fibers 101a) included in the inner reinforcing rubber layer are the same as those of the pneumatic tire. The short fiber (short fiber 101b) that is oriented along the circumferential direction (C direction) and contained in the outer reinforcing rubber layer is oriented along the tread width direction (W direction) of the pneumatic tire. And

  A third feature of the present invention relates to the first feature of the present invention, and is summarized in that the reinforcing rubber layer has a nonwoven fabric (nonwoven fabric 102) containing the short fibers.

  A fourth feature of the present invention is according to the third feature of the present invention, wherein the nonwoven fabric is a nonwoven fabric in which the short fibers are randomly oriented in the circumferential direction and the tread width direction of the pneumatic tire. And

  A fifth feature of the present invention relates to any one of the first to fourth features of the present invention, wherein the short fiber is a material selected from polyethylene, polypropylene, polyvinyl alcohol, and polymethyl methacrylate. It is a gist that it is formed alone or in combination.

  A sixth feature of the present invention relates to any one of the first to fifth features of the present invention, and is summarized in that a fiber length of the short fiber is 1 to 50 mm.

  A seventh feature of the present invention relates to any one of the first to sixth features of the present invention, and is summarized in that a thickness of the short fiber is 0.1 to 50 μm.

  According to the characteristics of the present invention, when a reinforcing rubber layer is provided on the surface of the tread, it is possible to provide a pneumatic tire that can more reliably prevent the occurrence of cracks in the rubber block formed on the tread.

1 is an exploded perspective view showing a part of a pneumatic tire according to a first embodiment of the present invention. It is sectional drawing of the tread width direction of the pneumatic tire which concerns on 1st Embodiment of this invention. FIG. 3 is an enlarged view of the vicinity of a tire equator line CL in the cross-sectional view shown in FIG. 2. It is sectional drawing along the circumferential direction of the pneumatic tire 1 shown in FIG. It is an enlarged view which expands and shows the peripheral part of the rubber block of the cross section along the circumferential direction of the pneumatic tire which concerns on 2nd Embodiment of this invention. It is an enlarged view which expands and shows the peripheral part of the rubber block of the cross section along the circumferential direction of the pneumatic tire which concerns on 3rd Embodiment of this invention.

  Next, an embodiment of a pneumatic tire according to the present invention will be described with reference to the drawings. Specifically, First Embodiment, 2. Second embodiment, 3. Third embodiment, 4. Examples, and 5. Other embodiments will be described.

  In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones. Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

1. First Embodiment (1) Configuration of Pneumatic Tire FIG. 1 is an exploded perspective view showing a part of a pneumatic tire 1 according to this embodiment. FIG. 2 is a cross-sectional view of the pneumatic tire 1 in the tread width direction (W direction). As shown in FIGS. 1 and 2, the pneumatic tire 1 has a carcass layer 12 that is a skeleton of the pneumatic tire 1.

  An inner liner 13 that is a highly airtight rubber layer corresponding to a tube is provided inside the carcass layer 12 in the tire radial direction. Both ends of the carcass layer 12 are supported by a pair of bead portions 14.

  A belt layer 15 is disposed outside the carcass layer 12 in the tire radial direction. The belt layer 15 includes a first belt layer 15a and a second belt layer 15b obtained by rubberizing a steel cord. The steel cords constituting the first belt layer 15a and the second belt layer 15b are arranged with a predetermined angle (for example, ± 25 degrees) with respect to the tire equator line CL.

  A tread portion 16 that contacts the road surface is provided on the outer side in the tire radial direction of the belt layer 15 (the first belt layer 15a and the second belt layer 15b).

  The tread portion 16 includes a tread rubber layer 16a and a reinforcing rubber layer 16b. A rubber block 17 is formed on the tread rubber layer 16a. The reinforcing rubber layer 16b is disposed on the outer side in the tire radial direction of the tread rubber layer 16a.

  The reinforcing rubber layer 16b covers the surface of the tread rubber layer 16a on which the rubber block 17 is formed. The reinforcing rubber layer 16 b covers the rubber block 17 and reinforces the rubber block 17.

  The reinforcing rubber layer 16b covers the surface 17a, the side surface 17b, the side surface 17c, and the edge portion 17d of the rubber block 17. The reinforcing rubber layer 16b covers a bottom portion 17e of a groove formed between the rubber blocks 17.

(2) Configuration of Reinforcing Rubber Layer Next, details of the reinforcing rubber layer 16b will be described with reference to FIGS. FIG. 3 is an enlarged view of the vicinity of the tire equator line CL in the cross-sectional view shown in FIG. FIG. 4 is a cross-sectional view along the circumferential direction C of the pneumatic tire 1 shown in FIG.

  The reinforcing rubber layer 16b includes the short fibers 101. As shown in FIG. 4, at least a part of the short fibers 101 is oriented along the circumferential direction C of the pneumatic tire 1.

  The short fiber 101 is a polyethylene-based fiber. In addition to polyethylene, polypropylene, polyvinyl alcohol, and polymethyl methacrylate fibers can be used. Moreover, these fibers can also be used in combination.

  The thickness d (see FIG. 3) along the tire radial direction of the reinforcing rubber layer 16b including the short fibers 101 is preferably in the range of 0.1 to 2 mm. When the thickness d is less than 0.1 mm, the rigidity of the reinforcing rubber layer 16b is smaller than the rigidity determined by the shape of the rubber block 17, and thus the effect of reinforcing the block wall surface is small. On the other hand, when the thickness d exceeds 2 mm, the ratio of the reinforcing rubber layer 16b to the entire rubber block 17 increases, and the heat generation increases. Moreover, rolling resistance becomes high.

  The fiber length L of the short fiber 101 is preferably 1 mm or more and 50 mm or less. If the fiber length L is shorter than 1 mm, sufficient rigidity of the reinforcing rubber layer 16b cannot be obtained. Further, when the fiber length L exceeds 50 mm, when kneading with the rubber to be blended, the fibers are entangled with each other or one fiber becomes a thread ball shape, so that a desired fiber orientation is obtained after vulcanization. Cannot be imparted to the tire surface uniformly and sufficiently.

  The thickness df of the short fiber 101 is preferably 0.1 μm or more and 50 μm or less. When the thickness df of the short fiber 101 is thinner than 0.1 μm, sufficient rigidity and strength of the reinforcing rubber layer 16b cannot be obtained. Moreover, when the thickness df of the short fiber exceeds 50 μm, the shape stability after vulcanization is lowered, and the contact area with the road surface is reduced. As a result, steering stability and braking performance are reduced.

(3) Action / Effect The pneumatic tire 1 includes a tread portion 16 that contacts the road surface, a rubber block 17 formed on the tread portion 16, and a reinforcing rubber layer that covers the surface of the tread portion 16 and reinforces the rubber block 17. 16b. The reinforcing rubber layer 16b includes the short fibers 101. At least a part of the short fibers 101 is oriented along the circumferential direction C of the pneumatic tire 1.

  According to the pneumatic tire 1, the short fibers 101 included in the reinforcing rubber layer 16 b are oriented along the circumferential direction C of the pneumatic tire 1. Thereby, the deformation | transformation of the circumferential direction C of the pneumatic tire 1 of the rubber block 17 is suppressed. For this reason, the shear rigidity along the circumferential direction C of the pneumatic tire 1 when a large driving force is applied to the pneumatic tire 1 can be increased.

  For example, when the pneumatic tire 1 is mounted on an automobile using an electric motor as a driving source, even if a large driving force is applied to the rubber block at the time of start and acceleration, the shear deformation amount of the rubber block is reduced. can do.

  Therefore, according to the pneumatic tire 1, the occurrence of cracks in the rubber block 17 formed in the tread portion 16 can be reliably prevented.

  The groove pattern formed between the rubber blocks 17 is related to the tire performance when the vehicle is started or braked (particularly on a wet road surface). The pneumatic tire 1 can increase the rigidity of the rubber block 17 without changing the conventional groove pattern, groove volume, and the like that are best formed in consideration of various conditions.

  The reinforcing rubber layer 16b disposed on the surface 17a portion is worn away by running and eventually disappears. However, the reinforcing rubber layer 16b disposed on the side surfaces 17b and 17c is not easily consumed. Thus, even if the reinforcing rubber layer 16b formed on the surface 17a is worn by running, the pneumatic tire 1 has shear rigidity due to the reinforcing rubber layer 16b disposed on the side surfaces 17b and 17c of the rubber block 17. Maintained.

  The reinforcing rubber layer 16b improves the compression rigidity of the edge portion 17d by reinforcing the edge portion 17d of the rubber block 17. As a result, the amount of deformation of the rubber block 17 when the tread portion 16 of the pneumatic tire 1 contacts is reduced. Therefore, pattern noise resulting from the block pattern of the rubber block 17 formed in the tread portion 16 is reduced.

2. Second Embodiment (1) Configuration of Pneumatic Tire Next, a pneumatic tire 2 shown as a second embodiment of the present invention will be described. The pneumatic tire 1 and the pneumatic tire 2 have different reinforcing rubber layers. Accordingly, only the configuration of the reinforcing rubber layer will be described below. In addition, in description of the following drawings, the same or similar code | symbol is attached | subjected to the same or similar part as the pneumatic tire 1 shown as 1st Embodiment, and detailed description is abbreviate | omitted.

(2) Configuration of Reinforcing Rubber Layer FIG. 5 is an enlarged view showing the periphery of the rubber block 17 having a cross section along the circumferential direction C of the pneumatic tire 2. The tread portion 16 includes a tread rubber layer 16a and a reinforcing rubber layer 160. A rubber block 17 is formed on the tread rubber layer 16a.

  The reinforcing rubber layer 160 is disposed outside the tread rubber layer 16a in the tire radial direction. The reinforcing rubber layer 160 covers the surface of the tread rubber layer 16a on which the rubber block 17 is formed. The reinforcing rubber layer 16 b covers the rubber block 17 and reinforces the rubber block 17. The reinforcing rubber layer 160 includes an inner reinforcing rubber layer 161 and an outer reinforcing rubber layer 162.

  The inner reinforcing rubber layer 161 includes short fibers 101a. The short fibers 101a are oriented along the circumferential direction C of the pneumatic tire 2 as shown in FIG.

  The outer reinforcing rubber layer 162 is provided on the outer side in the radial direction of the pneumatic tire 2 than the inner reinforcing rubber layer 161. The outer reinforcing rubber layer 162 includes short fibers 101b. As shown in FIG. 5, the short fibers 101 b are oriented along the tread width direction (direction perpendicular to the paper surface) of the pneumatic tire 2.

  The thickness d1 (see FIG. 5) along the tire radial direction of the inner reinforcing rubber layer 161 is preferably in the range of 0.05 to 1 mm. The thickness d2 (see FIG. 5) along the tire radial direction of the outer reinforcing rubber layer 162 is preferably in the range of 0.05 to 1 mm. Further, the thicknesses d1 and d2 may be different from each other.

  When the thickness d1 + d2 is smaller than 0.1 mm, the rigidity of the reinforcing rubber layer 160 is smaller than the rigidity determined by the shape of the rubber block 17, and thus the effect of reinforcing the block wall surface is small. On the other hand, when the thickness d1 + d2 exceeds 2 mm, the proportion of the reinforcing rubber layer 16b in the entire volume of the rubber block 17 increases, and the heat generation increases. Moreover, rolling resistance becomes high.

(3) Action / Effect The reinforcing rubber layer 160 has an inner reinforcing rubber layer 161 and an outer reinforcing rubber layer 162 provided on the radially outer side of the pneumatic tire 2 with respect to the inner reinforcing rubber layer 161. The short fibers 101a included in the layer 161 are oriented along the circumferential direction C of the pneumatic tire 2, and the short fibers 101b included in the outer reinforcing rubber layer 162 are aligned in the tread width direction (perpendicular to the paper surface) of the pneumatic tire 2. Direction).

  Thereby, the deformation | transformation of the circumferential direction C of the pneumatic tire 1 of the rubber block 17 is suppressed. For this reason, the shear rigidity of the pneumatic tire 2 when a large driving force is applied to the pneumatic tire 2 can be increased.

3. Third Embodiment (1) Configuration of Pneumatic Tire Next, a pneumatic tire 3 shown as a third embodiment of the present invention will be described. The pneumatic tire 1 and the pneumatic tire 3 have different reinforcing rubber layers. Accordingly, only the configuration of the reinforcing rubber layer will be described below.

(2) Configuration of Reinforcing Rubber Layer FIG. 6 is an enlarged view showing the periphery of the rubber block 17 having a cross section along the circumferential direction C of the pneumatic tire 3. The tread portion 16 includes a tread rubber layer 16a and a reinforcing rubber layer 163. The reinforcing rubber layer 163 is disposed outside the tread rubber layer 16a in the tire radial direction. The reinforcing rubber layer 163 covers the surface of the tread rubber layer 16a on which the rubber block 17 is formed. The reinforcing rubber layer 163 covers the rubber block 17 and reinforces the rubber block 17.

  The reinforcing rubber layer 163 includes the nonwoven fabric 102 containing short fibers. The nonwoven fabric 102 is a nonwoven fabric in which short fibers are randomly oriented in the circumferential direction C and the tread width direction of the pneumatic tire 3.

  As the nonwoven fabric 102, a nonwoven fabric made of short fibers of one or more synthetic fibers can be used. For example, a polyethylene nonwoven fabric can be used. The gap between the short fibers contained in the nonwoven fabric 102 and the thickness d4 of the nonwoven fabric can be selected as appropriate.

  The thickness d3 (see FIG. 6) of the reinforcing rubber layer 163 along the tire radial direction is preferably in the range of 0.1 to 2 mm. When the thickness d3 is smaller than 0.1 mm, the rigidity of the reinforcing rubber layer 163 is smaller than the rigidity determined by the shape of the rubber block 17, so that the effect of reinforcing the block wall surface is small. On the other hand, when the thickness d3 exceeds 2 mm, the proportion of the reinforcing rubber layer 16b in the entire volume of the rubber block 17 increases, and the heat generation increases. Moreover, rolling resistance becomes high.

(3) Action / Effect The reinforcing rubber layer 163 includes the nonwoven fabric 102 in which short fibers are randomly oriented in the circumferential direction C and the tread width direction of the pneumatic tire 3. Thereby, the deformation | transformation of the circumferential direction C of the pneumatic tire 1 of the rubber block 17 is suppressed. For this reason, the shear rigidity of the pneumatic tire 3 when a large driving force is applied to the pneumatic tire 3 can be increased.

4). Examples / Evaluation of Shear Stiffness Pneumatic tires were produced by changing the thickness of the reinforcing rubber layer, and the shear stiffness of the produced pneumatic tires was evaluated.

Tire size: 225 / 45R17
Rim size: 7.5J × 17
Air pressure: 240 kPa (same for front and rear wheels)
Test vehicle for actual running test: 2000cc displacement
Reinforcing rubber layer: normal tread rubber with oriented polyethylene fibers Thickness d: 1.0 mm (Example 1), 2.0 mm (Example 2) along the tire radial direction of the reinforcing rubber layer, reinforcing rubber layer None (Comparative Example 1), 3.0 mm (Comparative Example 2)
For the shear stiffness, the reaction force when the ground contact surface was displaced by 1 mm with a load applied to the tire was used. The results of shear rigidity are shown in Table 1.

  As shown in Table 1, in the pneumatic tires of Examples 1 and 2 in which the layer thickness d of the reinforcing rubber layer was 1 mm and 2 mm, the shear rigidity was improved. Moreover, since the displacement of the rubber block is also suppressed, it can be said that it has the effect of preventing the occurrence of cracks in the rubber block. On the other hand, when the thickness d of the reinforcing rubber layer was 3 mm as in the pneumatic tire of Comparative Example 2, it was confirmed that although the shear rigidity was improved, the rolling resistance was increased.

5). Other Embodiments As described above, the contents of the present invention have been disclosed through one embodiment of the present invention. However, it should be understood that the description and drawings constituting a part of this disclosure limit the present invention. Absent. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  In the above-described embodiment, the short fibers 101 included in the reinforcing rubber layer 16b and the short fibers 101a included in the inner reinforcing rubber layer 161 are oriented along the circumferential direction C of the pneumatic tire. However, the short fibers 101 and 101a may be oriented with a predetermined angle in the circumferential direction C of the pneumatic tire.

  The short fibers 101b included in the outer reinforcing rubber layer 162 are oriented along the trad width direction of the pneumatic tire. However, the short fibers 101b may be oriented with a predetermined angle with respect to the trad width direction of the pneumatic tire as long as they do not overlap with the orientation direction of the short fibers 101a.

  In the embodiment described above, the nonwoven fabric 102 is a nonwoven fabric in which short fibers are randomly oriented in the circumferential direction C and the tread width direction of the pneumatic tire. However, the short fibers of the nonwoven fabric 102 may be those in which the orientation is emphasized in any one of the circumferential direction C of the pneumatic tire, the tread width direction, or the radial direction of the pneumatic tire.

  In the above-described embodiment, the nonwoven fabric 102 included in the reinforcing rubber layer 163 is a single layer. However, a plurality of non-woven fabrics may be used in an overlapping manner. In this case, a plurality of nonwoven fabrics may be included in one reinforcing rubber layer. A plurality of reinforcing rubber layers containing one nonwoven fabric may be stacked.

  In the embodiment described above, the nonwoven fabric 102 included in the reinforcing rubber layer 163 is a short fiber nonwoven fabric, but may be a long fiber nonwoven fabric.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  1,2,3. . . Pneumatic tires, 11. . . Bead part, 12. . . Carcass layer, 13. . . Inner liner, 15. . . Belt layer, 15a. . . First belt layer, 15b. . . Second belt layer, 16. . . Tread portion, 16a ... tread rubber layer, 16b ... reinforcing rubber layer, 17 ... rubber block, 17a ... surface, 17b, 17c ... side face, 17e ... groove bottom, 101, 101a, 101b ... short fiber, 102 ... non-woven fabric, 161 ... Inner reinforcing rubber layer, 162 ... outer reinforcing rubber layer, 163 ... reinforcing rubber layer, CL ... tire equator line, d ... thickness of reinforcing rubber layer, d1 ... thickness of inner reinforcing rubber layer, d2 ... of outer reinforcing rubber layer Thickness, d3: thickness of reinforcing rubber layer, d4: thickness of non-woven fabric, df: thickness of short fiber, L: fiber length

Claims (7)

A tread that touches the road surface,
A rubber block formed on the tread;
A pneumatic tire that includes a reinforcing rubber layer that covers a surface of the tread and reinforces the rubber block,
The reinforcing rubber layer includes short fibers,
A pneumatic tire in which at least a part of the short fibers is oriented along a circumferential direction of the pneumatic tire. The reinforcing rubber layer is
An inner reinforcing rubber layer,
An outer reinforcing rubber layer provided on a radially outer side of the pneumatic tire than the inner reinforcing rubber layer;
The short fibers contained in the inner reinforcing rubber layer are oriented along the circumferential direction of the pneumatic tire,
The pneumatic tire according to claim 1, wherein the short fibers included in the outer reinforcing rubber layer are oriented along a tread width direction of the pneumatic tire.   The pneumatic tire according to claim 1, wherein the reinforcing rubber layer has a nonwoven fabric containing the short fibers.   The pneumatic tire according to claim 3, wherein the nonwoven fabric is a nonwoven fabric in which the short fibers are randomly oriented in the circumferential direction and the tread width direction of the pneumatic tire.   The pneumatic tire according to any one of claims 1 to 4, wherein the short fiber is formed of a material selected from polyethylene, polypropylene, polyvinyl alcohol, and polymethyl methacrylate alone or in combination.   The pneumatic tire according to any one of claims 1 to 5, wherein a fiber length of the short fibers is 1 to 50 mm.   The pneumatic tire according to any one of claims 1 to 6, wherein a thickness of the short fiber is 0.1 to 50 µm.

Images