JP5879779B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can ensure the effect of suppressing water splashing of fins even after the wear of the tire progresses.

  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

  An object of the present invention is to provide a pneumatic tire capable of ensuring the effect of suppressing water splashing of fins even after the wear of the tire proceeds.

In order to achieve the above object, a pneumatic tire according to the present invention is a pneumatic tire provided with a water spray suppressing fin in a buttress portion, and the fin protrudes from the profile of the buttress portion in the tire width direction. And has a ring-like and rib-like structure that extends continuously in the tire circumferential direction over the entire circumference of the tire, and is tread from the groove bottom of the deepest circumferential main groove in a sectional view in the tire meridian direction. When a curve m parallel to the profile of the surface is drawn and the intersection point of the curve m and the side wall surface of the tire is P, the intersection point of the fin and the profile of the paddle portion is located on the inner side in the tire radial direction from the intersection point P. disposed on the wall surface, and the tire radial direction outside of the wall surface of the fins, the tire in the tire meridian cross section view which has a wave-like shape having an amplitude in the tire radial direction radial direction And having a contour of a circular arc shape which is concave inwardly.

  In addition, the pneumatic tire according to the present invention draws a tangent line 1 from the tire ground contact end A to the fin and takes a contact B between the tangent line 1 and the fin in a sectional view in the tire meridian direction. The tire circumferential length L at the tire ground contact end A and the fin period T at the contact point B preferably have a relationship of 20 ≦ L / T ≦ 60.

  In addition, the pneumatic tire according to the present invention draws a tangent line 1 from the tire ground contact end A to the fin and takes a contact B between the tangent line 1 and the fin in a sectional view in the tire meridian direction. The amplitude W of the fin at the contact point B and the minimum value D1 of the distance D in the tire radial direction from the tire ground contact point A to the contact point B have a relationship of 0.2 ≦ W / D1 ≦ 0.9. preferable.

  In the pneumatic tire according to the present invention, since the fin has an amplitude W in the tire radial direction, a portion where the distance D between the fin and the road surface is appropriate remains even after the tire wear progresses. Thereby, even after the wear of the tire proceeds, there is an advantage that it is possible to appropriately ensure the water splash suppressing action of the fins.

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 view showing fins of the pneumatic tire depicted in FIG. 1. FIG. 3 is a perspective view showing fins of the pneumatic tire shown in FIG. 1. FIG. 4 is an explanatory view showing a wave shape of the fin shown in FIG. FIG. 5 is an explanatory view showing the action of the fin described in FIG. FIG. 6 is an explanatory view showing the action of the fin shown in FIG. FIG. 7 is an explanatory view showing a modification of the fin shown in FIG. FIG. 8 is an explanatory view showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention. FIG. 9 is a chart showing the results of the performance test of the pneumatic tire according to the embodiment of the present invention.

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

[Pneumatic tire]
FIG. 1 is a sectional view in the tire meridian direction showing a pneumatic tire 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, and a pair of sidewall rubbers 16, 16. (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 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 circumferential main groove 22 at the outermost side in the tire width direction 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. ing. The circumferential main groove means a circumferential groove having a groove depth of 8 mm or more.

  The pneumatic tire 1 has a narrow groove 4 and a thin rib 5. The narrow groove 4 is disposed in the vicinity of the tire ground contact edge and extends in the tire circumferential direction along the edge of the shoulder land portion 33. The fine ribs 5 are ribs defined by the fine grooves 4. In such a configuration, the uneven wear of the shoulder land portion 33 is suppressed when the thin rib 5 is grounded and actively worn during tire rolling.

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

  The pneumatic tire 1 includes fins 6 for suppressing water splash (see FIGS. 2 and 3). The fins 6 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. The fin 6 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). . Further, the fin 6 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 6 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 6 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 6, and a contact point between the tangent line 1 and the fin 6 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 6 has an arc-shaped outline, and the contact point B is positioned on the arc of the top. In addition, the wall surface on the outer side in the tire radial direction of the fin 6 is recessed inward of the tire 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 6 has an arcuate contour line that is concave inward in the tire radial direction, and further, the wall surface on the outer side in the tire radial direction of the fin 6 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]. In addition, the intersection (the end portion on the outer side in the tire radial direction at the base of the fin 6) between the fin 6 and the profile of the padless portion is disposed on the wall surface on the inner side in the tire radial direction from the intersection P. Further, the arrangement position and the height H of the fins 6 are adjusted so that the fins 6 do not exceed the maximum tire width. As a result, the shape and position of the fin 6 are optimized. The height H of the fin 6 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” 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 in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in 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.

[Wave shape of fin]
FIG. 4 is an explanatory view showing a wave shape of the fin shown in FIG. In FIG. 4, the left side shows the outline and position of the fin in a sectional view in the tire meridian direction, and the right side shows the positional relationship between the tire ground contact end A and the contact point B on the fin in the side view of the tread portion. .

  In a pneumatic tire having fins for suppressing water splash, if the distance between the fin and the road surface decreases due to the progress of wear of the tire, there is a possibility that the water splash suppression effect of the fin may decrease due to, for example, submersion of the fin. is there.

  Therefore, this pneumatic tire 1 employs the following configuration in order to maintain the effect of suppressing the splash of water on the fins even after the tire wear progresses.

  That is, in this pneumatic tire 1, the fin 6 extends in the tire circumferential direction, and the wall surface on the outer side in the tire radial direction of the fin 6 has a wavy shape having an amplitude in the tire radial direction (see FIG. 4).

  For example, in this embodiment, the fin 6 is disposed at a predetermined position of the buttress portion of the tire and has a rib-like structure continuous in the tire circumferential direction (see FIGS. 2 and 3). Further, the fin 6 extends in the tire circumferential direction while being smoothly curved in a sinusoidal shape (see FIG. 4). Further, the wall surface on the outer side in the tire radial direction of the fin 6 is periodically displaced while having a predetermined period T and a predetermined amplitude W with respect to the tire radial direction.

  5 and 6 are explanatory views showing the operation of the fin described in FIG. These figures show the water splash suppression effect of the fins when traveling on wet roads. FIG. 5 shows a state when the tire is new (when the wear rate is 0%), and FIG. 6 shows a state at the end of wear (when the wear rate is 80%).

  In this pneumatic tire 1, when traveling on a wet road, water splashes scattered by the fins 6 are guided in the tire width direction to suppress the splash height of the water splashes (see FIGS. 5 and 6). As a result, the influence of water splash on other vehicles traveling in the adjacent lane and the oncoming lane (water splash on the windshield of the passenger car and obstructing the driver's view) is suppressed.

  Further, when the tire is new, a portion mainly on the outer side in the tire radial direction out of the entire region of the fin 6 having the wavy shape guides water splash (see FIG. 5). Further, when the height from the road surface to the fins 6 decreases due to the progress of wear, a portion mainly inside the tire radial direction of the fins 6 guides water droplets (see FIG. 6). Thereby, the water splash suppression function of the fins 6 can be ensured throughout the entire period of use of the tire from when the tire is new to the end of wear.

  In the pneumatic tire 1, when the tire is new, the tire circumferential length L at the tire ground contact end A and the period T of the fins 6 at the contact point B preferably have a relationship of 20 ≦ L / T ≦ 60. 30 ≦ L / T ≦ 50 is more preferable (see FIG. 4). The tire circumferential length L and the period T of the fins 6 are measured as an unloaded condition while applying a prescribed internal pressure by mounting the tire on a prescribed rim.

  Further, in the pneumatic tire 1, when the tire is new, the amplitude W at the contact point B of the fin 6 and the minimum value D1 of the distance D in the tire radial direction from the tire ground contact end A to the contact point B are 0.2 ≦ It is preferable to have a relationship of W / D1 ≦ 0.9, and it is more preferable to have a relationship of 0.3 ≦ W / D1 ≦ 0.8 (see FIG. 4). That is, the distance D in the tire radial direction from the tire ground contact end A to the contact point B of the fin 6 changes periodically as it goes in the tire circumferential direction because the fin 6 has a wave shape. At this time, the amplitude W of the fin 6 is optimized with respect to the minimum value D1 of the distance D. Further, the maximum value D2 (= D1 + W) of the distance D is defined by the amplitude W. The distance D is measured as a no-load state while applying a specified internal pressure by mounting the tire on a specified rim.

  Further, the minimum value D1 of the distance D when the tire is new is preferably in the range of 15 [mm] ≦ D1 ≦ 45 [mm], and is in the range of 20 [mm] ≦ D1 ≦ 30 [mm]. It is more preferable. However, as described above, since the position of the fin 6 is defined by the relationship between the inclination angle θ of the tangent l and the curve m (see FIG. 2), the minimum value D1 of the distance D depends on the position of the fin 6. Limited.

  Further, in this embodiment, as described above, the fins 6 extend in the tire circumferential direction while being displaced in a sine wave shape (see FIG. 4). However, the present invention is not limited to this, and the fins 6 may extend in the tire circumferential direction while being displaced in a rectangular wave shape or a zigzag shape. For example, in the modification of FIG. 7, the fins 6 are periodically displaced in the tire circumferential direction while extending in a trapezoidal wave shape.

[effect]
As described above, the pneumatic tire 1 includes the fins 6 for suppressing water splash in the buttress portion (see FIGS. 2 and 3). In addition, the fin 6 extends in the tire circumferential direction, and the wall surface on the outer side in the tire radial direction of the fin 6 has a wave shape having an amplitude W in the tire radial direction (see FIG. 4).

  In such a configuration, since the fin 6 has the amplitude W in the tire radial direction, a portion where the distance D between the fin 6 and the road surface is appropriate remains even after the tire wear progresses. Thereby, even after the wear of the tire progresses, there is an advantage that the water splash suppressing action of the fin 6 can be appropriately secured.

  Moreover, in this structure, since the fin 6 has a wave shape, there exists an advantage that the rigidity of the fin 6 increases and the fining resistance of the fin 6 improves. This is particularly beneficial when the pneumatic tire 1 is a heavy load radial tire.

  Further, in this pneumatic tire 1, the tire circumferential length L at the tire contact point A when the tire is new and the period T of the fin 6 at the contact point B have a relationship of 20 ≦ L / T ≦ 60 (see FIG. 4). ). In such a configuration, since the relationship between the tire circumferential length L and the period T of the fin 6 is optimized, there is an advantage that the water splash suppressing action of the fin 6 can be appropriately secured. For example, when L / T <20, the water splash inhibiting action of the fin is reduced, which is not preferable. Further, when 60 <L / T, it is not preferable because when the fin comes into contact with a curb stone or the like, it is easy to receive an impact in the traveling direction and the fin is easily peeled off.

  Further, in the pneumatic tire 1, the amplitude W of the fin 6 at the contact B when the tire is new and the minimum value D1 of the distance D in the tire radial direction from the tire ground contact end A to the contact B are 0.2 ≦ W. /D1≦0.9 (see FIG. 4). In such a configuration, the relationship between the amplitude W of the fin 6 and the minimum value D1 of the distance D to the contact point B is optimized, so that the water droplet suppression action of the fin 6 can be appropriately ensured over the entire period of use of the tire. There is. For example, when W / D1 <0.2, the water splash inhibiting action of the fin 6 at the end of wear is reduced, which is not preferable. Further, when 0.9 <W / D1, it is not preferable because the water splash suppressing action of the fin 6 when the tire is new is reduced.

  8 and 9 are an explanatory diagram (FIG. 8) and a table (FIG. 9) 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) water splash suppression performance and (2) fin anti-bald performance were evaluated (see FIGS. 8 and 9). 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 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 Conventional Example 2. This evaluation is preferable as the numerical value increases. In addition, if the index at each stage is 0 or more when the wear rate is 0% (when the tire is new), the wear rate is 50% (middle wear), and the wear rate is 80% (end wear), the water splash suppression performance of the fin is appropriate. It can be said that it is demonstrated to.

  (2) 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 this observation result, index evaluation is performed with the conventional example 2 as a reference (100). This evaluation is preferable as the numerical value increases. In addition, if this evaluation is 90 or more, it can be said that the bald-proof performance is ensured appropriately.

  Examples 1-6 are the pneumatic tire 1 described in FIG. 1, the fin 6 for water splash suppression is formed in a buttress part, and the wall surface of the tire radial direction outer side of the fin 6 has a wavy shape. The tire extends in the tire circumferential direction (see FIGS. 2 to 4). 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 minimum value D1 of the distance D in the tire radial direction from the tire ground contact edge A to the contact point B is D1 = 20 [mm], and the height H of the fin 6 is H = 15 [mm].

  The pneumatic tire of Conventional Example 1 does not include a fin for suppressing water splash. The pneumatic tire of Conventional Example 2 includes the water splash suppression fins at a distance D = 15 [mm], but the fins extend linearly in the tire circumferential direction without having an amplitude.

  As shown in the test results, in the pneumatic tires 1 of Examples 1 to 6, since the fins 6 have a wavy shape, the water splash suppression performance is appropriately secured (see FIG. 8), and the water splash suppression effect. It can be seen that the maintenance performance and the anti-fining performance of the fins are improved (see FIG. 9). Further, when Examples 1 to 3 are compared, the relationship between the tire circumferential length L and the period T of the fins 6 is optimized, so that the maintenance performance of the water splash suppression effect and the fin resistance performance can be improved. I understand. In addition, when Examples 1, 4, and 5 are compared, the relationship between the amplitude W of the fin 6 and the minimum value D1 of the distance D to the contact point B is optimized, so that the maintenance performance of the water droplet suppression effect is improved. I understand that.

  DESCRIPTION OF SYMBOLS 1 Pneumatic tire, 21, 22 Circumferential main groove, 31-33 Land part, 4 Fine groove, 5 Fine rib, 6 Fin, 11 Bead core, 12 Bead filler, 121 Upper filler, 122 Lower filler, 13 Carcass layer, 14 Belt layer, 141-143 Belt ply, 15 tread rubber, 16 side wall rubber

Claims (5)

It is a pneumatic tire provided with fins for water splash suppression in the buttress part,
The fin has a shape protruding in the tire width direction from the profile of the buttress portion, and has an annular and rib-like structure continuously extending in the tire circumferential direction over the entire circumference of the tire,
When the curve m parallel to the profile of the tread surface is drawn from the groove bottom of the deepest circumferential main groove in a sectional view in the tire meridian direction, and the intersection of the curve m and the side wall surface of the tire is P, the fin And the intersection of the profile of the paddle part is disposed on the wall surface in the tire radial direction from the intersection P, and
Tire radial outer wall surface of the fin, and wherein a contour of a circular arc shape which is concave to the inner side in the tire radial direction in the tire meridian cross section view which has a wave-like shape having an amplitude in the tire radial direction Pneumatic tires. When a tangent line 1 is drawn from the tire ground contact end A to the fin and a contact B between the tangent line 1 and the fin is taken in a sectional view in the tire meridian direction,
2. The pneumatic tire according to claim 1, wherein a tire circumferential length L at the tire ground contact end A and a period T of the fins at the contact point B have a relationship of 20 ≦ L / T ≦ 60. When a tangent line 1 is drawn from the tire ground contact end A to the fin and a contact B between the tangent line 1 and the fin is taken in a sectional view in the tire meridian direction,
The amplitude W of the fin at the contact point B and the minimum value D1 of the distance D in the tire radial direction from the tire ground contact point A to the contact point B have a relationship of 0.2 ≦ W / D1 ≦ 0.9. Or the pneumatic tire of 2. A tire meridian cross-section view, one from the tire ground contact end inclination angle theta with respect to the tire axial direction of the tangent to the fins, 32 [deg] is in the range of ≦ θ ≦ 37 [deg] of claim 1-3 A pneumatic tire according to any one of the above. The pneumatic tire according to any one of claims 1 to 4 , wherein a height of the fin based on a profile of the buttress portion does not exceed a tire maximum width position in a cross-sectional view in a tire meridian direction.

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