JP5081476B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of reducing the temperature of a tire side portion that easily deteriorates.

  An increase in the temperature of the pneumatic tire is not preferable from the viewpoint of durability because it promotes a change with time such as a change in physical properties of the material or causes damage to the tread during high speed running. Especially for off-the-road radial (ORR) tires, truck bus radial (TBR) tires and run-flat tires during puncture (internal pressure 0 kPa) used for heavy loads, tires are used to improve durability. Reducing temperature has become a major issue. For example, in a run flat tire having a crescent-shaped reinforcing rubber, radial deformation concentrates on the reinforcing rubber during puncturing, and this portion reaches a very high temperature, which greatly affects the durability.

  As a means to reduce the tire temperature of pneumatic tires, there is a reinforcing member that reduces and suppresses the distortion of each component of the pneumatic tire (particularly, the carcass layer and the bead portion located in the sidewall portion). A technique for preventing the temperature rise due to the maximum is disclosed (for example, see Patent Document 1).

  However, in the conventional pneumatic tire described above, the provision of the reinforcing member may cause an unintended new failure such as an increase in tire weight or separation (peeling) at the reinforcing member. There is a problem that the normal running performance such as the riding comfort is deteriorated. In particular, in a run-flat tire, there is a concern that the vertical spring (elasticity in the tire longitudinal direction) during normal internal pressure travel is increased and the normal travel performance is deteriorated, and a technique that does not impair this normal travel performance is required.

As another means for reducing the tire temperature of a pneumatic tire, there is known one in which a large number of ridges are arranged on a rim guard of a flat pneumatic tire having a rim guard.
JP 2006-76431 A

  The technology for promoting the heat dissipation of the pneumatic tire described above increases the surface area of the tire to promote the heat dissipation. However, since a rubber material having low thermal conductivity is disposed on the outer peripheral side of the pneumatic tire, it is not possible to efficiently dissipate heat simply by increasing the tire surface area.

  Accordingly, the present invention has been made to solve the above-described problems, and is designed to efficiently reduce the temperature of a portion where deterioration in the tire side portion is caused by efficient heat dissipation, and to further improve durability. The object is to provide a tire.

  The present invention is a pneumatic tire provided on the tire surface of the tire side portion with turbulent flow generation projections extending from the inner peripheral side toward the outer peripheral side at intervals in the tire circumferential direction. The gist of the turbulent flow generation projection is that it has an edge when viewed in a radial cross section and is divided into a plurality of divided projection pieces via a gap.

  In the present invention, when the pneumatic tire rotates, an air flow that flows relatively along the tire circumferential direction is generated on the tire surface of the tire side portion, and this air flow becomes turbulent by the turbulent flow generation projection. As a result, the heat flows through the tire surface and actively exchanges heat with the tire surface. The turbulent flow flowing on the tire surface will be described in detail. Most of the air flow is a vertical turbulent flow that rises at the position of the divided projection piece and descends at a position where the divided projection piece does not exist. This vertical turbulent flow becomes a violent downward flow on the downstream side of the divided projection pieces and hits the tire surface, so that positive heat exchange is performed with the tire surface. Moreover, a part of air flow turns into the left-right turbulent flow which passes through the clearance gap between division | segmentation protrusion pieces. This left and right turbulent flow becomes a high-speed flow due to a rapid decrease in the flow path area and passes through the gap, so that positive heat exchange is performed with the tire surface during the passage process. The left-right turbulent flow that has passed through the gap expands in the left-right direction due to the rapid expansion of the flow path area, flows into the downstream side of the turbulent flow generation projection, and actively exchanges heat with the tire surface.

  Also, in the region where the turbulent flow generation projection is provided, the tire surface actively dissipates heat due to the turbulent flow, and particularly in the region near the gap, the tire surface dissipates heat due to the synergistic effect of the vertical turbulent flow and the lateral turbulent flow. More active. Therefore, the temperature of the pneumatic tire can be efficiently reduced by matching the position of the gap to a location where it is desired to suppress the temperature rise, and the durability can be further improved.

  In the present invention, the gap position of the turbulent flow generation projection is in the range of a height position of 0.7H1 to 1.2H1 from the bead base line, where H1 is the height from the bead base line to the maximum tire width. Is preferred. Since the position outside the range of 0.7 to 1.2 H1 from the bead baseline is too far away from the position of the failure nucleus (part where deterioration is likely to occur compared to other parts) in the tire side portion, the temperature of the failure nucleus It does not contribute much to the reduction, and the durability cannot be improved. As in the present invention, if it is within the range of 0.7 to 1.2H1 from the bead base line, it is close to the position of the failure nucleus in the tire side portion, so it contributes to the temperature reduction of the failure nucleus and improves the durability. be able to.

  The gist of the present invention is that the gap position of the turbulent flow generation projection is a failure nucleus position of the tire side portion. Therefore, since the temperature rise at the failure nucleus position can be surely prevented, the durability can be reliably improved.

  Moreover, the temperature rise of a tire maximum width position can be suppressed reliably by making the above-mentioned failure nucleus position of a tire side part into the position of a tire maximum width. Therefore, it is possible to reliably improve the durability in the vicinity of the maximum width where failure occurs most frequently during run flat.

  Furthermore, the temperature rise of a bead filler upper-end part position can be reliably suppressed by making the failure nucleus position of a tire side part into the upper end part of a bead filler. Therefore, it is possible to reliably suppress a temperature rise near the upper end portion of the bead filler where the failure is most frequent during normal internal pressure traveling, and it is possible to improve durability.

  In the present invention, the width of the gap is preferably in the range of 1.0 mm to 10 mm. If the gap is less than 1.0 mm, the left and right turbulent flow through the gap is too small and the amount of heat exchange due to the left and right turbulent flow becomes so small that no heat dissipation effect can be expected. If the gap exceeds 10 mm, the left and right turbulent flow through the gap The speed up will be slight and a sufficient heat dissipation effect cannot be expected. If the gap is in the range of 1.0 mm to 10 mm, the flow rate of the left and right turbulent flow to the extent that heat can be expected can be secured, and the speed can be increased, so that the heat release by the left and right turbulent flow can be reliably achieved. .

  Further, the ratio (w / e) of the width dimension (lower side width) w of the turbulent flow generation projection and the width dimension e of the gap is preferably in the range of 0.1 ≦ w / e ≦ 3.0. That is, if the w / e value is less than 0.1, the gap is too large and the negative without the turbulent flow generation projection increases. On the other hand, if the w / e value exceeds 3.0, the fluid friction resistance on the surface constituting the gap is large and the flow does not sufficiently enter. That is, if the w / e value is in the range of 0.1 ≦ w / e ≦ 3.0, the heat dissipation effect can be expected. Furthermore, it is more preferable that the ratio (w / e) of the width dimension w of the turbulent flow generation projection and the width dimension e of the gap is in the range of 0.2 ≦ w / e ≦ 1.5. The width e of the gap is preferably in the range of 1.0 to 10 mm.

  Further, as another feature, among the plurality of divided projection pieces, the divided projection piece located on the outermost side of the tire side portion has a lower projection height than the divided projection piece located on the inner circumference side. It may be set. By setting it as such a structure, it can suppress that the division | segmentation protrusion piece by the side of the tread of a tire rubs with a curb stone etc., for example.

  Furthermore, as another feature, the ratio of the width dimension e of the gap to the cross-sectional height SH from the bead base line is preferably in the range of 0.003 ≦ e / SH ≦ 0.15.

  Other features include 1.0 ≦ p / h ≦ 50.0 and 1.0 ≦ (p−, where h is the height of the turbulent flow generation projection, p is the pitch, and w is the width. It is preferable to satisfy the relationship of w) /w≦100.0. By defining the range of p / h as described above, the vertical turbulent state of the air flow can be roughly organized by p / h. If the pitch p is excessively finely divided, the gap between the turbulent flow generation projections Does not hit the tire surface as a downward flow. Moreover, if the pitch p is excessively widened, this is equivalent to the case where there is no shape processing of the turbulent flow generation projection.

  Further, (p−w) / w indicates the ratio of the width w of the turbulent flow generation protrusion to the pitch p. If this is too small, the turbulent flow generation protrusion relative to the area of the surface where heat release is desired to be improved. This is the same as the proportion of the surface area becomes equal. Since the turbulent flow generation projection is made of rubber and the effect of improving heat dissipation due to an increase in surface area cannot be expected, the minimum value of (p−w) / w is defined as 1.0.

  As another feature, the inclination angle θ of the turbulent flow generation projection with respect to the tire radial direction is preferably in the range of −70 ° ≦ θ ≦ 70 °. By defining the range of θ as described above, the air flow generated relatively by the rotating tire reliably collides with the circumferential surface of the turbulent flow generation projection. I can expect.

  Another feature is that the side tire portion includes a sidewall reinforcing layer. By adopting such a configuration, the sidewall reinforcing layer enables run-flat running, but the temperature rise of the failure nucleus at that time can be reduced as much as possible.

  ADVANTAGE OF THE INVENTION According to this invention, the efficient temperature reduction of the site | part in which degradation in a tire side part generate | occur | produces by efficient heat dissipation can be aimed at, and the pneumatic tire which improved durability further can be provided.

  Hereinafter, a run flat tire as a pneumatic tire according to an embodiment of the present invention will be described with reference to the drawings.

  1 to 7 show an embodiment of the present invention, FIG. 1 is a perspective view of a partially cutaway portion of a run-flat tire, FIG. 2 is a cross-sectional view of the main part of the run-flat tire, and FIG. 4 is a perspective view for explaining a turbulent flow generation state by a turbulent flow generation projection, FIG. 5 is a side view for explaining the flow of vertical turbulent flow, and FIG. 6 is a plane for explaining the flow of left and right turbulent flow. FIGS. 7A and 7B are perspective views showing the cross-sectional height SH, and FIG. 7B is an explanatory view showing the cross-sectional height SH from the bead base line and the width dimension e of the gap 11.

(Schematic configuration of run-flat tire)
As shown in FIGS. 1 to 3, the run-flat tire 1 that is a pneumatic tire includes a tread portion 2 that contacts a road surface, tire side portions 3 on both sides of the tire, and opening edges of the respective tire side portions 3. And a bead portion 4 provided.

  The bead portion 4 includes a bead core 6 </ b> A and a bead filler 6 </ b> B provided so as to go around along the edge of the opening of the tire side portion 3. For example, a steel cord or the like is used as the bead core 6A.

  A carcass layer 7 serving as a tire skeleton is provided inside the tread portion 2, the pair of tire side portions 3, and the pair of bead portions 4. A sidewall reinforcement layer 8 that reinforces the tire side portion 3 is provided on the inner side (in the tire width direction inner side) of the carcass layer 7 located on the tire side portion 3. The sidewall reinforcing layer 8 is formed of a crescent-shaped rubber stock in the cross section in the tire width direction.

  A plurality of belt layers (steel belt reinforcing layers 9A and 9B, circumferential reinforcing layer 9C) are provided inside the tread portion 2 and outside the carcass layer 7 in the tire radial direction.

  On the outer surface 3a that is the tire surface of each tire side portion 3, turbulent flow generation projections 10 extending from the inner peripheral side toward the outer peripheral side are provided at equal intervals in the tire circumferential direction. The inclination angle θ of the turbulent flow generation projection 10 with respect to the tire radial direction r is set in a range of −70 ° ≦ θ ≦ 70 ° (see FIG. 3). The range of the inclination angle θ is more preferably in the range of −30 ° ≦ θ ≦ 30 °.

<Configuration of projection for generating turbulent flow>
As shown in FIGS. 1 to 3 and the like, the turbulent flow generation projection 10 is divided into two divided projection pieces 12 and 13 through a gap. The division | segmentation protrusion pieces 12 and 13 have the edge parts 12E and 13E when it sees in a radial direction cross section. Moreover, as shown in FIG. 1, these division | segmentation protrusion pieces 12 and 13 have the edge parts 12F and 13F when it sees in the circumferential direction cross section. The height position of the gap 11 is set in the range of the height position of 0.7H1 to 1.2H1 from the bead base line, where H1 is the height from the bead base line (corresponding to the rim diameter) to the maximum tire width. In this embodiment, it is set to the height position H1 of the tire maximum width, which is the failure nucleus position. Here, the failure nucleus refers to a portion where deterioration is likely to occur compared to other portions.

  The gap 11 is formed by an inner peripheral end surface 12a of the outer divided projection piece 12, an outer peripheral end surface 13a of the inner divided projection piece 13, and an outer surface 3a of the tire side portion 3 disposed between the end surfaces 12a and 13a. It is formed by being surrounded. Both end surfaces 12a and 13a are formed on surfaces having an inclination angle of approximately 90 ° with respect to the outer surface 3a.

  As shown in FIGS. 3 to 6, the radial dimension of the gap 11, that is, the width dimension e is set in a range of 1.0 mm to 10 mm. In addition, the ratio (w / e) of the circumferential dimension of the turbulent flow generation projection 10, that is, the width dimension (lower side width: see FIG. 4) w and the width dimension e of the gap 11 is 0 / w. It is set in the range of 1 ≦ w / e ≦ 3.0. The w / e value is more preferably in the range of 0.2 ≦ w / e ≦ 1.5. The circumferential width dimension (lower side width) w of the turbulent flow generation projection 10 is preferably in the range of 0.5 mm to 5 mm. That is, if the lower side width of the turbulent flow generation projection 10 is less than 0.5 mm, the turbulent flow generation projection 10 may be vibrated by the air flow and weak in strength. When the lower side width w of the protrusion 10 exceeds 5 mm, the amount of heat stored in the turbulent flow generation protrusion 10 becomes too large. Therefore, by setting the lower side width of each turbulent flow generation projection 10 in the range of 0.5 mm to 5 mm, the heat radiation characteristics are improved while preventing inconvenience caused by providing the turbulent flow generation projection 10 on the tire side portion 3 as much as possible. Can be achieved.

  FIG. 7A is a perspective view showing the cross-sectional height SH from the bead base line, and FIG. 7B is an explanatory view showing the cross-sectional height SH from the bead base line and the width dimension e of the gap 11. The ratio of the width dimension e of the gap to the cross-sectional height SH from the bead base line is preferably in the range of 0.003 ≦ e / SH ≦ 0.15.

  In the present embodiment, when the height of the turbulent flow generation projection 10 is h, the pitch is p, and the width is w, 1.0 ≦ p / h ≦ 50.0 and 1.0 ≦ The dimension is set to satisfy the relationship of (p−w) /w≦100.0. The range of the p / h value is more preferably 10.0 ≦ p / h ≦ 20.0. The range of (p−w) / w value is more preferably 4.0 ≦ (p−w) /w≦39.0.

(Action of turbulent flow projection)
In the above configuration, when the run-flat tire 1 rotates, as shown in FIG. 4, an air flow a flowing relatively along the tire circumferential direction is generated on the outer surface 3 a of the tire side portion 3. a becomes a turbulent flow by the turbulent flow generation projection 10 and flows through the outer surface 3a, and positive heat exchange is performed with the outer surface 3a.

  The turbulent flow flowing on the outer peripheral surface will be described in detail. As shown in FIGS. 4 and 5, most of the air flow a rises at the position of the divided projection pieces 12 and 13, and In a non-existing position (the outer surface 3a between the adjacent divided projection pieces 12 (13) and 12 (13)), the vertical turbulent flow a1 descends. Since the vertical turbulent flow a1 becomes a violent downward flow on the downstream side of the divided projection pieces 12 and 13 and hits the outer surface 3a, positive heat exchange is performed with the outer surface 3a.

  Further, as shown in FIGS. 4 and 6, a part of the air flow a becomes a left-right turbulent flow a <b> 2 that passes through the gap 11 between the divided projection pieces 12 and 13. Since the left and right turbulent flow a2 passes through the gap 11 as a high-speed flow due to a rapid decrease in the flow path area, positive heat exchange is performed with the outer surface 3a during the passage of the gap 11. The left-right turbulent flow a2 after passing through the gap 11 expands in the left-right direction due to a rapid expansion of the flow path area, flows into the downstream side of each of the divided projection pieces 12, 13, and is positive between the outer surface 3a. Perform heat exchange. Since the immediately downstream region of each of the divided projection pieces 12 and 13 is a negative pressure region, the vertical turbulent flow a1 and the left and right turbulent flow a2 are swirled in the region immediately downstream of each of the divided protruding pieces 12 and 13 (FIGS. 5 and 6). The heat exchange is facilitated by the vortex.

  From the above, in the region of the tire side portion 3 where the turbulent flow generation projection 10 is provided, heat dissipation of the outer side surface 3a of the tire side portion 3 is actively performed by the turbulent flow. In particular, in the vicinity region E of the gap 11 (shown in FIG. 3), the outer surface 3a is more actively dissipated by the synergistic effect of the vertical turbulent flow a1 and the left and right turbulent flow a2. Therefore, the temperature of the part in the tire side part 3 corresponding to the vicinity area E of the gap 11 can be particularly reduced.

  In this embodiment, since the height position of the gap 11 is set at the position H1 of the tire maximum width which is the failure nucleus position, the temperature above the tire maximum width position H1 can be reliably prevented, so that the durability is improved. Improvement can be achieved reliably. That is, since the temperature above the tire maximum width position H1 can be reliably suppressed, it is possible to reliably improve the durability in the vicinity of the maximum width where failure occurs most frequently at the time of run flat.

  Here, the position of the gap 11 may be in the range of a height position of 0.7H1 to 1.2H1 from the bead base line, where H1 is the height from the bead base line to the maximum tire width. Since the position outside the range of 0.7 to 1.2H1 from the bead base line is too far away from the position of the failure nucleus of the tire side portion 3, it does not contribute much to the temperature reduction of the failure nucleus, and the durability can be improved. Can not. If it is within the range of 0.7 to 1.2H1 from the bead base line, it is close to the position of the failure nucleus of the tire side portion 3, and thus it contributes to the temperature reduction of the failure nucleus and can improve the durability.

  In this embodiment, the width dimension e of the gap 11 is in the range of 1.0 mm to 10 mm. If the gap 11 is less than 1.0 mm, the left and right turbulent flow a2 flowing through the gap 11 is too small and the amount of heat exchange by the left and right turbulent flow a2 becomes small, so that a heat dissipation effect cannot be expected. When the gap 11 exceeds 10 mm, the speed increase of the left and right turbulent flow a2 passing through the gap 11 becomes slight, and a heat dissipation effect cannot be expected. If the gap 11 is in the range of 1.0 mm to 10.0 mm, the flow rate of the left and right turbulent flow a2 that can be expected to release heat can be secured and the speed can be increased. Can be achieved reliably.

  In this embodiment, the w / e value is set in the range of 0.1 ≦ w / e ≦ 3.0. If the w / e value is less than 0.1, if the gap is too large, there will be no projection, and the region where the temperature will not be reduced becomes large. On the other hand, if the w / e value exceeds 3.0, the fluid friction resistance on the surface constituting the gap is large and the flow does not sufficiently enter. That is, if the w / e value is in the range of 0.1 ≦ w / e ≦ 3.0, the heat dissipation effect can be expected. Furthermore, it is more preferable that the ratio (w / e) of the width dimension w of the turbulent flow generation projection and the width dimension e of the gap is in the range of 0.2 ≦ w / e ≦ 1.5.

  In this embodiment, when the height of the turbulent flow generation projection 10 is h, the pitch is p, and the width (bottom side width: see FIG. 4) is w, 1.0 ≦ p / h ≦ 50.0, In addition, the relationship of 1.0 ≦ (p−w) /w≦100.0 is set to be satisfied. By defining the range of p / h as described above, the turbulent state of the air flow can be roughly organized by p / h. If the pitch p is excessively finely divided, the space between the turbulent flow generation projections 10 is reduced. It does not hit the outer surface 3a as a downward flow. Further, if the pitch p is excessively widened, it is equivalent to the case where the turbulent flow generation projection 10 is not formed.

  Further, (p−w) / w indicates the ratio of the width w of the turbulent flow generation protrusion 10 to the pitch p. If this is too small, the turbulent flow generation protrusion with respect to the area of the surface to be improved in heat dissipation. This is the same as the ratio of the surface area of 10 being equal. Since the turbulent flow generation projection 10 is made of rubber and cannot be expected to improve heat dissipation due to an increase in surface area, the minimum value of (p−w) / w is defined as 1.0.

  In this embodiment, the inclination angle θ of the turbulent flow generation projection 10 with respect to the tire radial direction r is in the range of −70 ° ≦ θ ≦ 70 °. By defining the range of θ as described above, the air flow a generated relatively by the rotating tire reliably collides with the surface in the tire circumferential direction of the turbulent flow generation projection 10. A heat dissipation effect can be expected.

  In this embodiment, the present invention is applied to a run flat tire 1 provided with a side wall reinforcing layer 8 in the side tire portion 3. The side wall reinforcing layer 8 enables run-flat running, but the temperature rise of the fault nucleus at that time can be reduced as much as possible.

  In particular, in this embodiment, since it has the edge portions 12E and 13E when viewed in the radial cross section of the divided projection pieces 12 and 13, the centrifugal force is applied from the inner diameter side to the outer diameter side as the run flat tire 1 rotates. There exists an effect | action which peels the flowing air flow, and this peeled air flow turns into a downward flow and abuts on the tire side part 3, and promotes heat exchange. Moreover, since these division | segmentation protrusion pieces 12 and 13 have the edge parts 12F and 13F when it sees in the circumferential cross section, an air flow gets over the division | segmentation protrusion pieces 12 and 13 with rotation of the run-flat tire 1. At this time, it is easily peeled off from the tire side portion 3. For this reason, the air flow once separated from the tire side portion 3 becomes a turbulent flow that suddenly descends and collides with the tire side portion 3 due to the negative pressure generated on the rear side in the tire rotation direction of the divided projection pieces 12 and 13. It has an effect of promoting heat exchange with the tire side portion 3.

(Other embodiments)
In the above embodiment, the gap 11 of the turbulent flow generation projection 10 is set to the tire maximum width position H1 that is the failure nucleus position, but is set to the upper end position of the bead filler 6B that is another failure nucleus position. Also good. If comprised in this way, since the temperature rise of the upper end part position of bead filler 6B can be controlled reliably, the temperature rise near the upper end part of bead filler 6B with the most trouble occurrence at the time of normal internal pressure traveling can be suppressed reliably, Durability can be improved.

  In the above embodiment, the gap 11 is provided only at one location of the turbulent flow generation projection 10, but may be provided at a plurality of locations of the turbulent flow generation projection 10. For example, there are two locations, the tire maximum width position H1 and the upper end position of the bead filler 6B.

  In the above embodiment, the turbulent flow generation projection 10 is provided over the entire circumference of the tire side portion 3, but the turbulent flow generation projection 10 may be provided only in a partial region of the tire side portion 3.

  In the above-described embodiment, the turbulent flow generation protrusions 10 are provided at equal intervals in the tire circumferential direction of the tire side portion 3, but the turbulent flow generation protrusions 10 may be provided at nonuniform intervals in the tire circumferential direction. .

  In the above embodiment, each of the divided projection pieces 12 and 13 has a rectangular parallelepiped shape, but various shapes are possible.

  In the above embodiment, the turbulent flow generation projection 10 is provided on the outer side surface 3 a of the tire side portion 3, but it may be provided on the inner side surface that is the surface of the tire side portion 3.

  In the above-described embodiment, an example in which the present invention is applied to the run-flat tire 1 has been described. However, pneumatic tires other than the run-flat tire 1, specifically, off-the-road radial (ORR) tires, truck bus radials (TBR). Of course, it can be applied to tires and the like. When applied to a heavy load tire, it is possible to reduce the temperature of the Ply end, which is a failure nucleus, and to improve the durability of the heavy load tire.

  In the above embodiment, the divided projection pieces 12 and 13 are set to have the same projection height, but the divided projection piece 12 positioned on the outermost side of the tire side portion 3 is divided into the divided projection pieces 13 positioned on the inner circumference side. The protrusion height may be set lower than that of. By setting it as such a structure, it can suppress that the division | segmentation protrusion piece 12 by the side of the tread of a tire rubs with a curb stone etc., for example.

(Example)
Next, examples will be described. In the examples and comparative examples, the endurance drum test was performed under the following conditions. As shown in FIG. 8, Comparative Example 1 is a tire provided with a turbulent flow generation projection without a gap, and Comparative Examples 2 and 3 and Examples 1, 2 and 3 have the same configuration as that of the above-described embodiment. The turbulent flow generation protrusion is provided, and the position of the gap is changed. In addition, the result (endurance evaluation) of the endurance drum test shows what indexed the endurance distance until failure occurred in FIG.

Tire size: 255 / 55R18
Rim used: 8.5JJ × 18
Internal pressure: 0 kPa
Load: 6.57kN
Speed: 80km / h
The definitions of p / h, (p−w) / w, θ and the like are as described above.

  It can be seen from FIG. 8 that the durability increases when the gap position of the turbulent flow generation projection is in the range of 0.7H1 to 1.2H1.

  FIG. 9 is a diagram showing the relationship between the ratio (p / h) of the ratio (p / h) between the pitch (p) and the height (h) of the turbulent flow generation projection and the heat transfer coefficient. The heat transfer coefficient on the vertical axis is indexed with the value of the turbulent flow generation projection having no gap as 100.

  From FIG. 9, it can be seen that the heat transfer coefficient increases when p / h is 1.0 or more and 50.0 or less. It can also be seen that the heat transfer coefficient is further increased when p / h is in the range of 10.0 to 20.0. Therefore, the turbulent flow generation projection 10 has a range of 1.0 ≦ p / h ≦ 50.0, and preferably a range of 10.0 ≦ p / h ≦ 20.0.

  FIG. 10 is a diagram showing the relationship between the inclination angle θ of the turbulent flow generation projection with respect to the tire radial direction r and the heat transfer coefficient. The heat transfer coefficient on the vertical axis is indexed with the value of the turbulent flow generation projection having no gap as 100.

  From FIG. 10, it can be seen that the heat transfer coefficient increases in the range of the inclination angle of 0 ° to 70 °. It is considered that the same heat transfer coefficient is exhibited even in the range of 0 ° to −70 °. Further, it is understood that the inclination angle θ is in the range of 0 ° to 30 ° (0 ° to −30 °), the index of heat transfer coefficient is approximately 117 or more, and the durability is further improved. For this reason, the inclination angle θ is preferably in the range of −70 ° ≦ θ70 °, and preferably in the range of −30 ° ≦ θ ≦ 30 °.

  FIG. 11 is a diagram showing the results of producing and testing pneumatic tires having different w / e values, and shows the relationship between the w / e value and the heat transfer coefficient. As shown in FIG. 11, when the w / e value is less than 0.1, if the gap is too large, there is no protrusion, and therefore the region where the temperature is not reduced becomes large, and when the w / e value exceeds 3.0. The fluid frictional resistance on the surfaces constituting the gap is large and the flow does not sufficiently enter, resulting in low thermal conductivity. That is, if the w / e value is in the range of 0.1 ≦ w / e ≦ 3.0, it can be seen that the heat dissipation effect can be expected. Furthermore, as can be seen from FIG. 11, the w / e value is more preferably in the range of 0.2 ≦ w / e ≦ 1.5.

1 is a partially cutaway perspective view of a run flat tire according to an embodiment of the present invention. It is principal part sectional drawing of the run flat tire concerning embodiment of this invention. 1 is a partial side view of a run flat tire according to an embodiment of the present invention. It is a perspective view explaining the turbulent flow generation state by the protrusion for turbulent flow generation. It is a side view explaining the flow of a vertical turbulent flow. It is a top view explaining the flow of a left-right turbulent flow. (A) is a perspective view which shows cross-sectional height SH, (b) is explanatory drawing which shows cross-sectional height SH from the bead base line, and the width dimension e of the clearance gap 11. FIG. It is a figure which shows the change of durability with respect to the clearance gap position of the protrusion for turbulent flow generation. It is a characteristic diagram which shows the relationship between p / h value and a heat transfer coefficient. It is a characteristic diagram which shows the relationship between inclination | tilt angle (theta) and a heat transfer rate. It is a characteristic diagram which shows the relationship between w / e value and thermal conductivity.

Explanation of symbols

1 Run-flat tire (pneumatic tire)
3 tire side part 3a outer side surface (tire surface)
6B Bead filler 8 Side wall reinforcing layer 10 Protrusion for generating turbulent flow 11 Gap 12 Dividing protrusion 13 Dividing protrusion 13

Claims (12)

A pneumatic tire provided on the tire surface of the tire side portion with turbulent flow generation projections extending from the inner peripheral side toward the outer peripheral side at intervals in the tire circumferential direction,
Each of the turbulent flow generation projections has an edge portion when viewed in a radial cross section, and is divided into a plurality of divided projection pieces via a gap ,
The ratio (w / e) of the width dimension w of the turbulent flow generation projection and the width dimension e of the gap is in the range of 0.1 ≦ w / e ≦ 3.0,
An inclination angle θ of the turbulent flow generation protrusion with respect to the tire radial direction is in a range of −70 ° ≦ θ ≦ 70 ° .   The gap position of the turbulent flow generation projection is in a range of a height position of 0.7H1 to 1.2H1 from the bead base line, where H1 is a height from the bead base line to the maximum tire width. The pneumatic tire according to claim 1.   The pneumatic tire according to claim 2, wherein the gap position of the turbulent flow generation projection is a failure nucleus position of the tire side portion.   The pneumatic tire according to claim 3, wherein the failure nucleus position of the tire side portion is a position of a tire maximum width.   The pneumatic tire according to claim 3, wherein the failure nucleus position of the tire side portion is an upper end portion of a bead filler. The ratio of the width e of the gap to the width w of the turbulent flow generation projection (w / e) is 1 to claim characterized in that it is a range of 0.2 ≦ w / e ≦ 1.5 The pneumatic tire according to claim 5 . Among the plurality of divided projection pieces, the divided projection piece located on the outermost peripheral side of the tire side portion has a projection height set lower than that of the divided projection piece located on the inner circumferential side. The pneumatic tire according to any one of claims 1 to 6 , wherein the pneumatic tire is characterized. Ratio of the width dimension e of the gap with respect to the section height SH from the bead base line, any one of claims 1 to 7, characterized in that in the range of 0.003 ≦ e / SH ≦ 0.15 The pneumatic tire described in one item. When the height of the turbulent flow generation projection is h, the pitch is p, and the width is w, 1.0 ≦ p / h ≦ 50.0 and 1.0 ≦ (p−w) / w ≦ The pneumatic tire according to any one of claims 1 to 8 , wherein a relationship of 100.0 is satisfied. The pneumatic tire according to any one of claims 1 to 9 , wherein the side tire portion includes a sidewall reinforcing layer. The pneumatic tire according to any one of claims 1 to 10 , wherein the pneumatic tire is a run-flat tire.   The pneumatic tire according to any one of claims 1 to 10, wherein the pneumatic tire is a heavy-duty vehicle tire.

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