JP2010018125A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving the pebble biting-in resistance performance of the tire. <P>SOLUTION: In this pneumatic tire 1, a peripheral groove 2 has a shape of which groove width is narrower as going to a groove depth direction by changing a groove wall angle. A groove wall angle α of a groove wall surface on a groove opening part side of the peripheral groove 2 and a groove wall angle β of the groove wall surface on a groove bottom part side have the following relationship, α>β. Further, a height H from a groove bottom of the peripheral groove 2 to an inflection point X of the groove wall angles α and β varies as going toward the tire peripheral direction. The height H is in a region of 0.3≤H/GD≤0.5 with respect to a groove depth GD of the peripheral groove 2. Furthermore, a groove width L in an optional inflection point X and a groove width L' in an inflection point X having a height H' lower than the height H of the inflection X have a relationship, L/L'. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of improving the stone-resisting performance of the tire.

  In recent pneumatic tires (particularly, heavy duty pneumatic tires), there is a problem that stone drilling and tread separation are likely to occur due to stone biting in circumferential grooves. In order to solve such a problem, a circumferential groove having a funnel shape is employed. As a conventional pneumatic tire having such a configuration, a technique described in Patent Document 1 is known.

JP 05-278414 A

  It is an object of the present invention to provide a pneumatic tire that can improve the stone biting performance of the tire.

  In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire having a plurality of circumferential grooves extending in the tire circumferential direction, and the tire is mounted on a prescribed rim and imparted with a prescribed internal pressure. Between the normal line drawn in the groove depth direction from the tread surface and the groove wall surface of the circumferential groove in a sectional view in the groove width direction and groove depth direction of the circumferential groove in the inflated state. When the angle is referred to as a groove wall angle, at least one of the circumferential grooves has a shape in which the groove width is narrowed toward the groove depth direction by changing the groove wall angle on at least one side, and the circumferential groove The groove wall angle α of the groove wall surface on the groove opening side of the directional groove and the groove wall angle β of the groove wall surface on the groove bottom side have a relationship of α> β, and the groove wall angle α from the groove bottom of the circumferential groove , The height H up to the inflection point of β changes as it goes in the tire circumferential direction And the groove width L at any inflection point and the height of the inflection point are within the range of 0.3 ≦ H / GD ≦ 0.5 with respect to the groove depth GD of the circumferential groove. The groove width L ′ at the inflection point having a height H ′ lower than the height H has a relationship of L / L ′.

  In this pneumatic tire, (1) since the height H from the groove bottom of the circumferential groove to the inflection points of the groove wall angles α and β changes as it goes in the tire circumferential direction, it is caught in the circumferential groove. The boulder is easy to move to a position having a wide groove width L. This makes it easier for the bited stone to be discharged from the circumferential groove, and there is an advantage that the stone biting performance of the tire is improved. (2) The height H from the groove bottom of the circumferential groove to the inflection point X of the groove wall angles α and β is optimized with respect to the groove depth GD of the circumferential groove (0.3 ≦ H / GD ≦ 0.5), there is an advantage that the stone resistance performance of the tire is further improved. (3) The groove width L at an arbitrary inflection point X and the groove width L ′ at the inflection point X having a height H ′ lower than the height H of the inflection point X are L / L ′. Therefore, there is an advantage that damage to the belt layer of the tire due to the bite stone is prevented.

  In the pneumatic tire according to the present invention, the groove wall angle α and the groove wall angle β have a relationship of 0 [deg] <β <α <25 [deg].

  In this pneumatic tire, the range of the groove wall angles α and β is optimized, so that there is an advantage that the stone biting performance of the tire is further improved.

  In the pneumatic tire according to the present invention, the groove width L and the groove width L ′ have a relationship of 1.2 ≦ L / L ′ ≦ 3.0.

  In this pneumatic tire, the range of the groove width L 'at the inflection point X having a high height H and the groove width L' at the inflection point X having a low height H 'is optimized. There is an advantage that the stone biting performance is effectively improved.

  In the pneumatic tire according to the present invention, the groove width L and the groove width L ′ and the groove width W on the tread surface of the circumferential groove are 0.2 ≦ L / W ≦ 0.7 and 0.2 ≦ L. '/W≦0.7.

  In this pneumatic tire, the range of the groove width L ′ at the inflection point X having the high height H and the groove width L ′ at the inflection point X having the low height H ′ is further optimized. There is an advantage that the stone biting performance is effectively improved.

  In the pneumatic tire according to the present invention, the pitch P at which the inflection point varies in the tire circumferential direction and the groove width W on the tread surface of the circumferential groove satisfy 1.5 ≦ P / W ≦ 4.0. Have a relationship.

  In this pneumatic tire, since the pitch P of the inflection point X is optimized, there is an advantage that the stone resistance performance of the tire is effectively improved.

  Further, the pneumatic tire according to the present invention has a groove wall angle α at an arbitrary inflection point and a groove wall angle α at the inflection point having a height H ′ lower than the height H of the inflection point. And have a relationship of α <α.

  In this pneumatic tire, when the groove wall angle α ′ at the inflection point having a low height H ′ is set large, the trapped stone is easily discharged from the circumferential groove 2. Thereby, there exists an advantage which the stone biting performance of a tire improves effectively.

  The pneumatic tire according to the present invention is applied to a heavy duty radial tire.

  This pneumatic tire has an advantage that the effect by the stone-resisting performance of the tire to which the heavy duty radial tire is applied is remarkably obtained.

  According to the pneumatic tire of the present invention, (1) since the height H from the groove bottom of the circumferential groove to the inflection points of the groove wall angles α and β changes as it goes in the tire circumferential direction, The stone caught in the directional groove is easy to move to a position having a wide groove width L. This makes it easier for the bited stone to be discharged from the circumferential groove, and there is an advantage that the stone biting performance of the tire is improved. (2) The height H from the groove bottom of the circumferential groove to the inflection point X of the groove wall angles α and β is optimized with respect to the groove depth GD of the circumferential groove (0.3 ≦ H / GD ≦ 0.5), there is an advantage that the stone resistance performance of the tire is further improved. (3) The groove width L at an arbitrary inflection point X and the groove width L ′ at the inflection point X having a height H ′ lower than the height H of the inflection point X are L / L ′. Therefore, there is an advantage that damage to the belt layer of the tire due to the bite stone is prevented.

  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.

  FIG. 1 is a perspective view showing a circumferential groove of a pneumatic tire according to an embodiment of the present invention. 2 is a tread plan view (FIG. 2), a cross-sectional view taken along the line AA (FIG. 3), a cross-sectional view taken along the line BB (FIG. 4), and C-- showing the circumferential grooves of the pneumatic tire shown in FIG. It is C sectional view (FIG. 5). 6-9 is explanatory drawing which shows the effect | action of the pneumatic tire described in FIG. FIG. 10 is a chart showing the results of the performance test of the pneumatic tire according to the example of the present invention.

[Pneumatic tire]
The pneumatic tire 1 has a plurality of circumferential grooves 2 extending in the tire circumferential direction and a plurality of land portions 3 and 3 defined by the circumferential grooves 2 in a tread portion (see FIG. 1). ). For example, in this embodiment, a plurality of circumferential grooves 2 are formed in the tread portion, and a plurality of ribs 3 and 3 are formed by these circumferential grooves 2. Thereby, a tread pattern based on the rib 3 is formed (not shown).

  Here, in a cross-sectional view in the groove width direction and the groove depth direction of the circumferential groove 2 in a state in which the tire is mounted on the specified rim and inflated with a specified internal pressure, the tread tread surface (of the land portion 3) The angle formed between the normal line drawn from the tread surface in the groove depth direction and the groove wall surface of the circumferential groove 2 is referred to as a groove wall angle (see FIG. 4).

  At this time, at least one circumferential groove 2 has a shape (funnel shape) in which the groove width (interval between the opposing groove wall surfaces) is narrowed toward the groove depth direction by changing the groove wall angle on at least one side. (See FIG. 4). Further, the groove wall angle α of the groove wall surface on the groove opening side of the circumferential groove 2 and the groove wall angle β of the groove wall surface on the groove bottom side have a relationship of α> β. For example, in this embodiment, the left and right groove wall angles of the circumferential groove 2 are configured symmetrically with respect to the groove center line in a sectional view of the circumferential groove 2 in the groove width direction and the groove depth direction. Further, the groove wall surface of the circumferential groove 2 has a groove wall angle α on the groove opening side and a groove wall angle β on the groove bottom side. The groove wall angle α on the groove opening side and the groove wall angle β on the groove bottom side have a relationship of α> β. Further, the groove wall surface of the circumferential groove 2 has inflection points X of groove wall angles α and β in the middle of the groove depth direction. The groove wall surface of the circumferential groove 2 is bent in a convex shape at the inflection point X, and the circumferential groove 2 having a substantially funnel-like cross-sectional shape is formed. Thereby, the shape of the circumferential groove | channel 2 is devised so that the bitten stone may be easily discharged.

  Not limited to this, the circumferential groove 2 may have a shape in which the groove width is narrowed toward the groove depth direction by changing the groove wall angle on only one side (not shown). That is, only one groove wall surface of the circumferential groove 2 may have the inflection point X to change the groove wall angle, and the other groove wall surface may be configured with a substantially uniform groove wall angle.

  Further, the height H from the groove bottom of the circumferential groove 2 to the inflection point X of the groove wall angles α and β changes as it goes in the tire circumferential direction (see FIGS. 1 and 3). At this time, the height H of the inflection point X is in the range of 0.3 ≦ H / GD ≦ 0.5 with respect to the groove depth GD of the circumferential groove 2. For example, in this embodiment, the height H of the inflection point X changes in a zigzag shape as it goes in the tire circumferential direction (groove length direction).

  Further, the groove width L (interval of the groove wall surfaces facing each other) L at an arbitrary inflection point X, and the groove width L ′ at the inflection point X having a height H ′ lower than the height H of the inflection point X, Have a relationship of L / L ′ (see FIGS. 1, 2, 4 and 5). For example, in this embodiment, since the height H of the inflection point X changes in a zigzag shape as it goes in the tire circumferential direction, the position of the inflection point X is the groove width in plan view of the tread portion. It changes in a zigzag shape in the direction. Then, the groove width L at the inflection point X changes as it goes in the tire circumferential direction. Further, at the inflection point X having a high height H, the groove width L at the height H is set large, and at the inflection point X having a low height H ′, the groove width at the height H ′ is small. Is set.

  In this embodiment, the prescribed rim refers to an “applied rim” prescribed in JATMA, a “Design Rim” prescribed in TRA, or a “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 “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 the case of a tire for a passenger car, the specified internal pressure is an air pressure of 180 [kPa], and the specified load is 88 [%] of the maximum load capacity.

  In the pneumatic tire 1, as described above, the groove width L is set large at the inflection point X having a high height H, and the groove width L ′ is set small at the inflection point X having a low height H ′. (See FIGS. 1, 2, 4 and 5). Therefore, when a stone bites into a position having a high height H, since the height H is high, the stone does not easily reach the groove bottom, and the occurrence of stone drilling is suppressed (see FIGS. 6 and 7). Then, as the wear of the tire proceeds, the bite stones are discharged. Further, when stones are caught in a position having a low height H ′, when the circumferential grooves 2 are opened and closed by the contact pressure during rolling of the tire, the caught stones move in the circumferential grooves 2 in the groove length direction. (See FIGS. 8 and 9). Then, when the stone gradually moves to a position having a high height H and a wide groove width L, the bite stone is easily discharged from the circumferential groove 2. Thereby, the stone resistance performance of a tire improves.

[effect]
As described above, in this pneumatic tire 1, (1) the height H from the groove bottom of the circumferential groove 2 to the inflection points X of the groove wall angles α and β changes as it goes in the tire circumferential direction. Therefore, the stones biting into the circumferential groove 2 can easily move to a position having a wide groove width L. This makes it easier for the bited stone to be discharged from the circumferential groove 2, which has the advantage of improving the stone biting performance of the tire.

  (2) The height H from the groove bottom of the circumferential groove 2 to the inflection point X of the groove wall angles α and β is optimized with respect to the groove depth GD of the circumferential groove 2 (0.3 ≦ H /GD≦0.5), there is an advantage of further improving the stone biting performance of the tire. For example, if H / GD <0.3 or 0.5 <H / GD, the tire's stone-resisting performance cannot be sufficiently obtained.

  (3) The groove width L at an arbitrary inflection point X and the groove width L ′ at the inflection point X having a height H ′ lower than the height H of the inflection point X are L / L ′. Therefore, there is an advantage that damage to the belt layer of the tire due to the bite stone is prevented. For example, when L <L ′, since the wide groove width L is located at the inflection point X having a low height H ′, there is a possibility that the bite stone may damage the belt layer of the tire.

[Modification]
In this pneumatic tire 1, the groove wall angle α on the groove opening side of the circumferential groove 2 and the groove wall angle β on the groove bottom side have a relationship of 0 [deg] <β <α <25 [deg]. It is preferable to have (refer FIG. 4). In such a configuration, since the range of the groove wall angles α and β is optimized, there is an advantage that the stone-resisting performance of the tire is further improved.

  In this pneumatic tire 1, the groove width L at the inflection point X having a high height H and the groove width L ′ at the inflection point X having a low height H ′ are 1.2 ≦ L / L ′. It is preferable to have a relationship of ≦ 3.0 (see FIGS. 4 and 5). In such a configuration, since the range of the groove widths L and L ′ is optimized, there is an advantage that the stone biting performance of the tire is effectively improved.

  In the pneumatic tire 1, the groove width L at the inflection point X having the high height H and the groove width L ′ at the inflection point X having the low height H ′ are the tread surface of the circumferential groove 2. It is preferable to have a relationship of 0.2 ≦ L / W ≦ 0.7 and 0.2 ≦ L ′ / W ≦ 0.7 with respect to the groove width W (see FIGS. 4 and 5). In such a configuration, since the ranges of the groove widths L and L ′ are further optimized, there is an advantage that the stone-resisting performance of the tire is effectively improved.

  In the pneumatic tire 1, the pitch P at which the inflection point X (height H and width L) varies in the tire circumferential direction and the groove width W on the tread surface of the circumferential groove 2 are 1.5 ≦ P /. It is preferable to have a relationship of W ≦ 4.0 (see FIGS. 1 to 3). In such a configuration, since the pitch P of the inflection point X is optimized, there is an advantage of effectively improving the stone biting performance of the tire. For example, when P / W <1.5, the fluctuation of the height H and the width L of the inflection point X is too large, so that the bite stone is difficult to move in the circumferential groove 2 and is not easily discharged. In addition, when 4.0 <P / W, the fluctuation of the height H and the width L of the inflection point X is too gentle, so that it is difficult to discharge the bite stone.

  In the pneumatic tire 1, the groove wall angle α at the inflection point X having a high height H ′ and the groove wall angle α ′ at the inflection point X having a low height H ′ satisfy α <α ′. It is preferable to have a relationship (see FIGS. 4 and 5). In such a configuration, the rock wall angle α ′ at the inflection point X having a low height H ′ is set to be large, so that the trapped stone is easily discharged from the circumferential groove 2. Thereby, there exists an advantage which the stone biting performance of a tire improves effectively.

  However, the present invention is not limited to this, and the groove wall angle α on the opening side of the circumferential groove 2 may be set constant (α = α ′) in the tire circumferential direction. Further, at the inflection point X at the same position, the groove wall angle on the inner side in the tire width direction (tread portion center region side) and the groove wall angle on the outer side in the tire width direction (tread portion shoulder region side) may not be equal.

[Applicable to]
The pneumatic tire 1 is preferably a heavy duty radial tire. In such a pneumatic tire, stone drilling due to stone biting tends to occur easily. Therefore, by using such a pneumatic tire as an application target, there is an advantage that the effect by the stone-resisting performance of the tire can be remarkably obtained.

[performance test]
In this example, a performance test relating to stone biting performance was performed on a plurality of pneumatic tires having different conditions (see FIG. 10). In this performance test, a pneumatic tire having a tire size of 11R22.5 (14PR) is assembled to a rim having a rim size of 22.5 × 8.25, and the pneumatic tire has an air pressure of 700 [kPa] and a load of 26.73 [kN]. Is loaded. Further, the four pneumatic tires are mounted on the drive shaft of a test vehicle that is a 2-D vehicle. Then, this test vehicle travels 10 km on the non-paved road, and the number of stone bites of the tire after traveling is measured. Then, based on the measurement result, index evaluation using the conventional example as a reference (100) is performed. In this evaluation, the larger the numerical value, the smaller the number of stone bites.

  The pneumatic tire of the conventional example has a shape (funnel shape) in which the groove width becomes narrower toward the groove depth direction by changing the groove wall angle of the circumferential groove. The groove wall angle α of the groove wall surface on the groove opening side of the circumferential groove and the groove wall angle β of the groove wall surface on the groove bottom side have a relationship of α> β. Further, the height from the groove bottom of the circumferential groove to the inflection points of the groove wall angles α and β is set constant over the entire tire circumference. For this reason, the groove width at the inflection point is also set to be constant in the tire circumferential direction.

  The pneumatic tires 1 of Invention Examples 1 to 7 have a shape in which the groove width is narrowed as the circumferential groove 2 moves in the groove depth direction by changing the groove wall angle (FIGS. 1 to FIG. 1). 5). The groove wall angle α of the groove wall surface on the groove opening side of the circumferential groove 2 and the groove wall angle β of the groove wall surface on the groove bottom side have a relationship of α> β. Further, the height H from the groove bottom of the circumferential groove 2 to the inflection points X of the groove wall angles α and β changes as it goes in the tire circumferential direction. Further, the height H of the inflection point X is set within the range of 0.3 ≦ H / GD ≦ 0.5 with respect to the groove depth GD of the circumferential groove 2. Further, the groove width L at the inflection point X and the groove width L ′ at the inflection point X having a height H ′ lower than the height H of the inflection point X have a relationship of L / L ′. ing.

  As shown in the test results, it can be seen that in the pneumatic tires 1 of Invention Examples 1 to 7, the stone biting performance of the tire is improved (see FIG. 10). Further, comparing Invention Examples 1 and 2 and Comparative Example 1, the ratio L / L ′ of the groove widths L and L ′ at the inflection point X is optimized, so that the stone resistance performance of the tire is improved. I understand. Further, comparing Invention Example 1 and Comparative Example 2, the ratio H / GD between the height H of the inflection point X and the groove depth GD of the circumferential groove 2 is optimized, so that the stone resistance of the tire is increased. It can be seen that the biting performance is improved. Further, when Invention Examples 3 to 6 are compared, the ratio P / W between the pitch P at which the inflection point X varies in the tire circumferential direction and the groove width W on the tread surface of the circumferential groove 2 is optimized. Thus, it is understood that the stone biting performance of the tire is improved. Further, when Invention Example 4 and Invention Example 7 are compared, the groove wall angle α at the inflection point having a high height H ′ and the groove wall angle α ′ at the inflection point having a low height H ′ are obtained. It can be seen that by having a relationship of α <α ′, the stone biting performance of the tire is improved.

  As described above, the pneumatic tire according to the present invention is useful in that the stone biting performance of the tire can be improved.

It is a perspective view which shows the circumferential groove | channel of the pneumatic tire concerning the Example of this invention. It is a tread top view which shows the circumferential direction groove | channel of the pneumatic tire described in FIG. It is AA sectional view which shows the circumferential groove | channel of the pneumatic tire described in FIG. It is a BB sectional view showing the circumferential direction groove of the pneumatic tire indicated in FIG. It is CC sectional view which shows the circumferential groove | channel of the pneumatic tire described in FIG. It is explanatory drawing which shows the effect | action of the pneumatic tire described in FIG. It is explanatory drawing which shows the effect | action of the pneumatic tire described in FIG. It is explanatory drawing which shows the effect | action of the pneumatic tire described in FIG. It is explanatory drawing which shows the effect | action of the pneumatic tire described in FIG. It is a graph which shows the result of the performance test of the pneumatic tire concerning the Example of this invention.

Explanation of symbols

1 Pneumatic tire 2 Circumferential groove 3 Land

Claims (7)

A pneumatic tire having a plurality of circumferential grooves extending in the tire circumferential direction,
Pulled from the tread tread in the groove depth direction in a sectional view in the groove width direction and groove depth direction of the circumferential groove when the tire is mounted on the specified rim and inflated with a specified internal pressure. When the angle formed between the normal line and the groove wall surface of the circumferential groove is called a groove wall angle,
At least one of the circumferential grooves has a shape in which the groove width is narrowed toward the groove depth direction by changing the groove wall angle on at least one side, and the groove wall surface on the groove opening side of the circumferential groove. The groove wall angle α of the groove and the groove wall angle β of the groove wall surface on the groove bottom side have a relationship of α> β, and the height from the groove bottom of the circumferential groove to the inflection points of the groove wall angles α, β H changes as it goes in the tire circumferential direction and is within the range of 0.3 ≦ H / GD ≦ 0.5 with respect to the groove depth GD of the circumferential groove, and any inflection point The pneumatic tire is characterized in that the groove width L at the inflection point and the groove width L ′ having a height H ′ lower than the inflection point height H have a relationship of L / L ′.   The pneumatic tire according to claim 1, wherein the groove wall angle α and the groove wall angle β have a relationship of 0 [deg] <β <α <25 [deg].   The pneumatic tire according to claim 1, wherein the groove width L and the groove width L ′ have a relationship of 1.2 ≦ L / L ′ ≦ 3.0.   The groove width L and the groove width L ′ and the groove width W on the tread surface of the circumferential groove have a relationship of 0.2 ≦ L / W ≦ 0.7 and 0.2 ≦ L ′ / W ≦ 0.7. The pneumatic tire according to any one of claims 1 to 3.   The pitch P at which the inflection point varies in the tire circumferential direction and the groove width W on the tread surface of the circumferential groove have a relationship of 1.5 ≦ P / W ≦ 4.0. The pneumatic tire according to one.   The groove wall angle α at any inflection point and the groove wall angle α ′ at the inflection point having a height H ′ lower than the height H of the inflection point have a relationship of α <α ′. The pneumatic tire according to any one of claims 1 to 5.   The pneumatic tire according to any one of claims 1 to 6, which is applied to a heavy duty radial tire.

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