JP5966348B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire that can improve the chain mounting property of the tire.

  In recent years, a heavy load pneumatic tire employs a structure in which fins are provided in a buttress portion of a tire as a countermeasure against water splashes generated when traveling on a wet road surface. And by this fin, the kinetic energy of water splash is absorbed and the scattering height of water splash is reduced. As a conventional pneumatic tire employing such a configuration, a technique described in Patent Document 1 is known.

JP 2000-318410 A

  However, in the conventional pneumatic tire, when a chain for running on a snowy road is attached to the tire, the chain is difficult to be hooked by the fin, and there is a problem that the chain attachment property of the tire is lowered.

  Therefore, the present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving the chain mounting property of the tire.

In order to achieve the above object, the pneumatic tire of the present invention includes lug grooves that extend in the tire width direction and open to the buttress portion in the left and right shoulder land portions, and extend continuously in the tire circumferential direction. a pneumatic tire comprising at least one of the buttress portions rib-shaped fins, the fins have a plurality of cut portions which are arranged over the entire circumference of the top portion of the fin in the tire circumferential direction at predetermined intervals And the arrangement | positioning space | interval Pc of the said notch part and the groove width W of the said lug groove have the relationship of 0.3 <= Pc / W <= 1.0 .
The pneumatic tire according to the present invention includes lug grooves extending in the tire width direction and opening in the buttress portion in the left and right shoulder land portions, and rib-shaped fins extending continuously in the tire circumferential direction. The at least one buttress portion is a pneumatic tire, and the fin has a plurality of cut portions arranged over the entire circumference of the top of the fin at predetermined intervals in the tire circumferential direction, and When defining the region T from the opening end of the lug groove on the buttress portion side to the distance of ± W in the tire circumferential direction, where the groove width of the lug groove is W, the number N of the cut portions arranged in each region T Is in the range of 1 ≦ N ≦ 5.

  In the pneumatic tire according to the present invention, since the fin has the cut portion, the rigidity of the fin in the cut portion is reduced. As a result, the fin can be easily deformed when the chain for running on a snowy road is attached to the tire. Thereby, there exists an advantage which the chain mounting property of a tire improves.

FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing fins of the pneumatic tire shown in FIG. FIG. 3 is a perspective sectional view showing fins of the pneumatic tire shown in FIG. 1. FIG. 4 is an explanatory view showing the operation of the pneumatic tire shown in FIG. FIG. 5 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

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

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire according to an embodiment of the present invention. This figure shows a heavy duty radial tire applied to a truck, a bus or the like. Reference sign CL is a tire equator plane.

  The pneumatic tire 1 includes a pair of bead cores 11, 11, a pair of bead fillers 12, 12, a carcass layer 13, a belt layer 14, a tread rubber 15, a pair of sidewall rubbers 16, 16, and a pair. Bead rubbers 17 and 17 (see FIG. 1). The pair of bead cores 11 and 11 has an annular structure and constitutes the core of the left and right bead portions. The pair of bead fillers 12 and 12 includes an upper filler 121 and a lower filler 122, which are disposed on the outer periphery in the tire radial direction of the pair of bead cores 11 and 11, respectively, to reinforce the bead portion. The carcass layer 13 has a single-layer structure and is bridged in a toroidal shape between the left and right bead cores 11 and 11 to constitute a tire skeleton. Further, both end portions of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The belt layer 14 includes a pair of stacked belt plies 141 to 143 and is disposed on the outer periphery in the tire radial direction of the carcass layer 13. These belt plies 141 to 143 are configured by arranging and rolling a plurality of belt cords made of steel or organic fiber material, and by crossing the belt cords in different directions in the tire circumferential direction. Configure the structure. The tread rubber 15 is disposed on the outer circumference in the tire radial direction of the carcass layer 13 and the belt layer 14 to constitute a tread portion of the tire. The pair of side wall rubbers 16 and 16 are respectively arranged on the outer side in the tire width direction of the carcass layer 13 to constitute left and right side wall portions. The pair of bead rubbers 17, 17 are arranged on the outer sides in the tire width direction of the left and right bead cores 11, 11 and the bead fillers 12, 12 to constitute left and right bead portions.

  The pneumatic tire 1 includes a plurality of circumferential main grooves 21 and 22 extending in the tire circumferential direction and a plurality of land portions 31 to 33 that are partitioned by the circumferential main grooves 21 and 22. Prepare for the department. In this embodiment, the outermost circumferential main groove 22 has the deepest groove depth, and the second land portion 32 and the shoulder land portion 33 are partitioned by the circumferential main groove 22. The circumferential main groove means a circumferential groove having a groove depth of 8 mm or more.

  Further, the pneumatic tire 1 has lug grooves 4 extending in the tire width direction in the left and right shoulder land portions 33 and 33. The lug groove 4 opens to the outermost circumferential main groove 22 at one end, and opens to the buttress portion at the other end. A plurality of lug grooves 4 are arranged at predetermined intervals in the tire circumferential direction. The lug groove refers to a lateral groove having a groove depth of 2.0 [mm] or more.

[Fin for water splash control]
2 and 3 are an enlarged cross-sectional view (FIG. 2) and a perspective cross-sectional view (FIG. 3) showing the fins of the pneumatic tire shown in FIG.

  This pneumatic tire 1 includes fins 5 for suppressing water splash (see FIGS. 2 and 3). The fins 5 are formed on at least the buttress portions on the left and right sides of the tire at the buttress portion located on the outer side in the vehicle width direction when the vehicle is mounted. Further, the fin 5 has a shape protruding in the tire width direction from the profile of the buttress portion, and has a wall surface on the outer side in the tire radial direction (tire contact end side) and a wall surface on the inner side in the tire radial direction (side wall portion side). . The fin 5 has an annular and rib-like structure that continuously extends over the entire circumference of the tire.

  The buttress portion refers to a side wall portion between the tire ground contact end and the tire maximum width position. Further, the fin 5 may be integrally formed with the sidewall rubber 16 at the time of tire vulcanization molding, or may be adhered and attached after the tire vulcanization molding.

  Further, the shape and position of the fin 5 are set as follows.

  First, A is a tire ground contact end in a sectional view in the tire meridian direction. Further, a tangent line 1 is drawn from the tire ground contact end A to the fin 5, and a contact point between the tangent line 1 and the fin 5 is defined as B. Further, the inclination angle of the tangent line 1 with respect to the tire axial direction is defined as θ. Further, a curve m parallel to the profile of the tread surface is drawn from the groove bottom of the deepest circumferential main groove (here, the circumferential main groove 22 on the outermost side in the tire width direction). Let P be the intersection with.

  At this time, the top of the fin 5 has an arc-shaped contour line, and the contact point B is located on the top of the arc. In addition, the wall surface on the outer side in the tire radial direction of the fin 5 is recessed toward the tire inner side with respect to the tangent l. Thus, a side wall surface that is curved or bent in the tire axial direction from the tire ground contact end A toward the contact point B is formed. In this embodiment, the wall surface on the outer side in the tire radial direction of the fin 5 has an arc-shaped contour line that is recessed in the inner side in the tire radial direction, and further, the wall surface on the outer side in the tire radial direction of the fin 5 and the buttress portion. The profile is smoothly connected via an arc-shaped contour line recessed in the tire.

  Further, the inclination angle θ of the tangent l is in the range of θ <45 [deg], and more preferably in the range of 32 [deg] ≦ θ ≦ 37 [deg]. Further, the intersection point Q between the fin 5 and the profile of the buttress portion (the end portion on the outer side in the tire radial direction at the base of the fin 5) is disposed on the wall surface on the inner side in the tire radial direction from the intersection point P. Moreover, the arrangement position and the height H of the fin 5 are adjusted so that the fin 5 does not exceed the tire maximum width. As a result, the shape and position of the fin 5 are optimized. The height H of the fin 5 is measured with reference to the profile of the buttress portion.

  The tire ground contact edge means a tire when a tire is attached to a specified rim and applied with a specified internal pressure and is placed perpendicular to a flat plate in a stationary state and a load corresponding to a specified load is applied. An end in the tire axial direction on the contact surface with the flat plate.

  The tread end of the tire refers to both end portions of the tread pattern portion of the tire when the tire is mounted on the specified rim and applied with the specified internal pressure and is in an unloaded state.

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

[Fin notch]
Moreover, in this pneumatic tire 1, the fin 5 has the notch part 51 in the top part (refer FIG. 3). The top portion of the fin 5 refers to a portion of the fin 5 that is on the outermost side in the tire width direction. Therefore, the top of the fin 5 and the contact point B in FIG.

  The cut portion 51 of the fin 5 is a sipe-like or slit-like cut and is formed together with the fin 5 using a molding die. Specifically, the width (thickness) Wc of the cut portion 51 is in the range of 0.5 [mm] ≦ Wc ≦ 1.5 [mm].

  Further, the length Lc of the cut portion 51 and the width S of the fin 5 have a relationship of 0.15 ≦ Lc / S ≦ 0.50. The length Lc of the cut portion 51 is measured as an extending range of the cut portion 51 in the tire width direction. The width S of the fin 5 takes an intersection point Q between the fin 5 and the profile of the buttress portion, and is measured as a distance in the tire width direction from the intersection point Q to the top of the fin 5. Note that the intersection point Q and the intersection point P in FIG. 2 do not necessarily match. Further, the width S of the fin 5 and the height H of the fin 5 in FIG.

  Further, the fin 5 has a plurality of cut portions 51 arranged in the tire circumferential direction, and an arrangement interval Pc of the cut portions 51 and a groove width W of the lug groove 4 are 0.3 ≦ Pc / W ≦. 1.0 relationship. That is, the arrangement interval Pc of the cut portions 51 is set to be equal to or less than the groove width W of the lug groove 4.

  Further, the groove width of the lug groove 4 is W, and a region T from the opening end of the lug groove 4 on the buttress portion side to a distance of ± W in the tire circumferential direction is taken. That is, a section having a distance W × 2 in the tire circumferential direction around the opening end of the lug groove 4 is defined as a region T. At this time, the arrangement number N of the cut portions 51 in the region T is in the range of 1 ≦ N ≦ 5 (N: natural number). Therefore, the cut portions 51 of the fins 5 are arranged at substantially the same position (region T) in the tire circumferential direction with respect to the opening ends of the lug grooves 4.

  In the configuration of FIG. 3, the fin 5 has a straight cut portion 51 extending from the top of the fin 5 in the tire width direction. Further, the plurality of cut portions 51 are arranged at a predetermined arrangement interval Pc (= W) in the tire circumferential direction, and are arranged over the entire circumference of the fin 5. Further, the lug groove 4 has a straight shape parallel to the tire width direction, and one notch 51 is arranged on the groove center line n of the lug groove 4.

[effect]
As described above, the pneumatic tire 1 includes the left and right shoulder land portions 33 and 33 with the lug grooves 4 extending in the tire width direction and opening in the buttress portion (see FIG. 3). The pneumatic tire 1 includes rib-shaped fins 5 extending continuously in the tire circumferential direction in at least one buttress portion. Further, the fin 5 has a cut portion 51 at the top of the fin 5.

  In such a configuration, the fin 5 has the cut portions 51, whereby the rigidity of the fins 5 in the cut portions 51 is reduced. Then, as shown in FIG. 4, the fin 5 can be easily deformed when the chain C for running on a snowy road is attached to the tire. As a result, there is an advantage that the chain mounting property of the tire is improved, and the deterioration of the braking / driving performance of the tire due to the shift of the chain position can be suppressed.

  In the pneumatic tire 1, the fin 5 has a plurality of cut portions 51 arranged in the tire circumferential direction. Further, the arrangement interval Pc of the cut portions 51 and the groove width W of the lug groove 4 have a relationship of 0.3 ≦ Pc / W ≦ 1.0 (see FIG. 3). In such a configuration, since 0.3 ≦ Pc / W, there is an advantage that the rigidity of the fin 5 is ensured, and the mogging of the fin 5 starting from the cut portion 51 is suppressed. Further, since Pc / W ≦ 1.0, there is an advantage that the number of the cut portions 51 is ensured and the effect of improving the chain mounting property by the cut portions 51 can be appropriately obtained.

  Further, in this pneumatic tire 1, when the groove width of the lug groove 4 is W and the region T from the opening end on the buttress portion side of the lug groove 4 to a distance of ± W in the tire circumferential direction is taken, The arrangement number N of the cut portions 51 is in the range of 1 ≦ N ≦ 5 (see FIG. 3). In such a configuration, the cut portion 51 of the fin 5 is arranged at substantially the same position (region T) in the tire circumferential direction with respect to the opening end of the lug groove 4, so that the arrangement position of the cut portion 51 is optimized. . Thereby, there exists an advantage by which the improvement effect of the chain mounting property by the notch part 51 is acquired appropriately. Further, since N ≦ 5, there is an advantage that the rigidity of the fins 5 is ensured, and the mogging of the fins 5 starting from the cut portions 51 is suppressed.

  Moreover, in this pneumatic tire 1, the length Lc of the cut portion 51 and the width S of the fin 5 have a relationship of 0.15 ≦ Lc / S ≦ 0.50 (see FIG. 3). In such a configuration, since Lc / S ≦ 0.50, there is an advantage that the rigidity of the fin 5 is appropriately secured and the fining resistance of the fin 5 is improved. Further, since 0.15 ≦ Lc / S, there is an advantage that the length Lc of the cut portion 51 is appropriately secured, and the effect of improving the chain mounting property by the cut portion 51 can be appropriately obtained.

  Moreover, in this pneumatic tire 1, the width Wc of the cut portion 51 is in the range of 0.5 [mm] ≦ Wc ≦ 1.5 [mm] (see FIG. 3). In such a configuration, since Wc ≦ 1.5 [mm], there is an advantage that the water splash passing through the cut portion 51 is reduced and the water splash suppression performance by the fins 5 is appropriately ensured. Further, since 0.5 [mm] ≦ Wc, the deformation of the fins 5 when the chain is mounted increases, and there is an advantage that the chain mounting property is improved.

  FIG. 5 is a table showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

  In this example, for a plurality of different pneumatic tires, (1) chain mountability, (2) water splash suppression performance of fins, and (3) fin resistance performance were evaluated (see FIG. 5). ). In these performance tests, a pneumatic tire with a tire size of 275 / 80R22.5 was assembled to a rim with a rim size of 22.5 × 7.50, and the pneumatic tire had a pneumatic pressure of 900 [kPa] and a maximum load capacity specified by JATMA. Is granted. A pneumatic tire is mounted on a test vehicle which is a truck having a total weight of 25 tons.

  (1) In the evaluation of chain wearability, a test vehicle equipped with a chain travels on a snowy road at 30 [km / h], and the amount of displacement [mm] in the tire circumferential direction of the chain after traveling a predetermined distance is measured. The The smaller the positional deviation, the better. If it is 100 [mm] or less, it is recognized that there is an advantage over the conventional example.

  (2) In the evaluation regarding the water splash suppression performance, the test vehicle travels straight on a wet road having a water depth of 10 [mm], and the splash height of the water splash is photographed with a video camera and measured. Then, based on the measurement result, index evaluation is performed with reference to (100) when the tire is new in the conventional example. This evaluation is more preferable as the numerical value is larger. If it is 95 or more, it can be said that the performance is appropriately secured.

  (3) In the evaluation regarding anti-baldness performance, the number of occurrences of fin baldness is observed after the test vehicle repeats the running test of the curbstone having a height of 250 [mm] 20 times. Then, based on the observation result, index evaluation using the conventional example as a reference (100) is performed. This evaluation is more preferable as the numerical value is larger. If it is 95 or more, it can be said that the performance is appropriately secured.

  The pneumatic tire 1 of Example 1 has the configuration described in FIGS. Further, when the tire is new, the tire circumferential length L is L = 3035 [mm], the inclination angle θ of the tangent l is θ = 35 [deg], and the groove depth G of the deepest circumferential main groove 22 is G = 18 [mm]. Further, the distance D in the tire radial direction from the tire ground contact edge A to the contact point B is D = 20 [mm], and the height H of the fin 5 is H = 15 [mm]. Moreover, the width W of the lug groove 4 is W = 13.0 [mm], and the width S of the fin 5 is 12.0 [mm]. Moreover, the pneumatic tire 1 of Examples 2-12 is a modification of the pneumatic tire 1 of Example 1.

  In the conventional pneumatic tire, in the pneumatic tire 1 of the first embodiment, the fins 5 do not have the cut portions 51 (not shown).

  As shown in the test results, in the pneumatic tires 1 of Examples 1 to 12, it is understood that the chain mounting property is improved, and the water splash suppressing performance and the bald resistance performance are appropriately secured.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 21, 22 Circumferential main groove, 31-33 Land part, 4 Lag groove, 5 Fin, 51 Cut part, 11 Bead core, 12 Bead filler, 121 Upper filler, 122 Lower filler, 13 Carcass layer, 14 Belt layer, 15 tread rubber, 16 side wall rubber, 17 bead rubber, 141-143 belt ply

Claims (7)

A pneumatic tire having lug grooves extending in the tire width direction and opening in the buttress portion in the left and right shoulder land portions and rib-like fins extending continuously in the tire circumferential direction in at least one buttress portion Because
The fins have a plurality of cut portions which are arranged over the entire circumference of the top portion of the fin in the tire circumferential direction at predetermined intervals, and,
A pneumatic tire characterized in that an arrangement interval Pc of the cut portions and a groove width W of the lug groove have a relationship of 0.3 ≦ Pc / W ≦ 1.0 . A pneumatic tire provided with left and right shoulder land portions having lug grooves extending in the tire width direction and opening in the buttress portion, and having rib-shaped fins extending continuously in the tire circumferential direction in at least one buttress portion. Because
The fins have a plurality of cut portions which are arranged over the entire circumference of the top portion of the fin in the tire circumferential direction at predetermined intervals, and,
When defining the region T from the opening end of the lug groove on the buttress portion side to the distance of ± W in the tire circumferential direction, where the groove width of the lug groove is W, the number of the cut portions arranged in each region T A pneumatic tire , wherein N is in a range of 1 ≦ N ≦ 5 . The length Lc of the notch portion, and the width S of the fins, the pneumatic tire according to claim 1 or 2 having a relation 0.15 ≦ Lc / S ≦ 0.50. The pneumatic tire according to any one of claims 1 to 3 , wherein a width Wc of the cut portion is in a range of 0.5 [mm] ≤ Wc ≤ 1.5 [mm].   The pneumatic tire according to any one of claims 1 to 4, wherein a top portion of the fin has an arc-shaped contour line in a sectional view in the tire meridian direction.   The pneumatic tire according to any one of claims 1 to 5, wherein a wall surface on the tire radial outer side of the fin has an arcuate contour line that is concave on the tire radial inner side in a sectional view in the tire meridian direction. tire.   The pneumatic tire according to any one of claims 1 to 6, wherein the fin is located on the inner side in the tire width direction from the tire maximum width position.

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