JP4980815B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire provided with ridges for generating turbulent flow on a tire side surface.

  In general, a temperature rise of a 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. To improve durability, especially in off-the-road radial (ORR) tires, truck bus radial (TBR) tires, and run-flat tires during puncture travel (with an internal pressure of 0 [kPa]), which are used under heavy loads Reducing the tire temperature is a major issue. For example, in a run-flat tire having a crescent-shaped reinforcing rubber, deformation in the tire radial direction is concentrated on the reinforcing rubber during puncturing, and this portion reaches a very high temperature, which greatly affects the durability.

  As a tire temperature reducing means, a means has been proposed in which heat generation is suppressed by using a reinforcing member for the purpose of reducing or suppressing distortion of a tire constituent member. However, when a reinforcing member is used, an unintended failure occurs, and particularly in a run-flat tire, the vertical spring (elasticity in the tire radial direction) during normal internal pressure running usually increases and the riding comfort deteriorates. The performance may be affected. For this reason, a new tire temperature reduction means that does not impair normal performance has been demanded.

As a new tire temperature reduction means, by forming turbulent flow generation protrusions along the tire radial direction in the tire side portion, the generation of turbulent flow with fast flow velocity on the tire surface was promoted, and the cooling effect was improved. There is a thing (refer patent document 1). Since the rubber constituting the tire is a material with poor thermal conductivity, it is known that the cooling effect by promoting the generation of turbulent flow is more effective than expanding the heat radiation area and aiming for the cooling effect. .
International Publication No. 2007/032405 Pamphlet

  When the height of the turbulent flow generating ridge from the tire side surface is constant in the tire radial direction, the inventor of the present invention has the air flow from the tire radial inner side toward the tire radial outer side. It has been found that an efficient cooling effect cannot be obtained by peeling (weakening) on the outer side in the tire radial direction at the tire maximum position width position on the side surface.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a pneumatic tire capable of realizing a more efficient cooling effect.

  The pneumatic tire according to the present invention is formed on the inner side in the tire radial direction at the tire maximum width position on the surface of the tire side portion, extending along the tire radial direction, and spaced apart along the tire circumferential direction. A plurality of inner turbulent flow generating ridges are formed, and are extended along the tire radial direction outward in the tire radial direction from the tire maximum width position on the surface of the tire side portion, and along the tire circumferential direction A plurality of outer turbulent flow generating ridges formed at intervals are formed, and the height from the tire side surface of the inner turbulent flow generating ridge and the outer turbulent flow generating ridge is the inner side in the tire radial direction. The height from the surface of the tire side portion at the end is set to be higher than the height from the surface of the tire side portion at the outer end in the tire radial direction.

  According to the pneumatic tire of the present invention, the height of the inner end portion in the tire radial direction of the inner turbulent flow generating ridge formed on the inner side in the tire radial direction with the tire maximum width position as a boundary is set to the height of the outer end portion in the tire radial direction. By making it higher than the height, it is possible to suppress the separation of the air flow at the tire maximum width position, and to increase the amount of air contacting the tire side surface, thereby realizing a more efficient cooling effect. be able to.

  According to the pneumatic tire according to the present invention, the height of the inner end in the tire radial direction of the outer turbulent flow generating ridge formed on the outer side in the tire radial direction with the tire maximum width position as a boundary is set to the height of the outer end in the tire radial direction. By making it higher than the height, it is possible to suppress the separation of the air flow on the outer side in the tire radial direction and to increase the amount of air that contacts the tire side surface, thereby realizing a more efficient cooling effect. be able to.

  Hereinafter, with reference to the drawings, a detailed description will be given of the configuration of a run-flat tire including a turbulent flow generation ridge according to an embodiment of the present invention. In the present specification, the “turbulent flow generating ridge” is used to generate or promote turbulent flow. Further, in the embodiment shown below, the present invention is applied to a run-flat tire provided with a reinforcing rubber having a crescent-shaped cross section in the tire radial direction in the tire side portion, but the scope of the present invention is applied to a run-flat tire. The present invention is not limited, and the present invention can also be applied to heavy load tires such as off-the-road radial (ORR) tires and truck bus radial (TBR) tires.

[Schematic configuration of run-flat tire]
As shown in FIGS. 1 and 2, a run flat tire 1 according to an embodiment of the present invention includes a tread portion 2 that contacts a road surface, a tire side portion 3 formed on both sides of the tire, and each tire side portion. 3 and the bead part 4 provided along the opening edge of 3. As shown in FIG. 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 opening edge of the tire side portion 3. An example of the bead core 6A is a steel cord.

  The run-flat tire 1 further includes a carcass layer 7 serving as a tire skeleton as shown in FIG. A side wall reinforcing layer 8 as a reinforcing rubber is provided inside the carcass layer 7 located in the tire side portion 3 (in the tire width direction). The sidewall reinforcing layer 8 is formed of a crescent-shaped rubber stock in the cross section in the tire width direction. As shown in FIG. 2, a plurality of belt layers (steel belt reinforcing layers 9 and 10, circumferential reinforcing layer 11) are provided outside the carcass layer 7 in the tire radial direction. A tread portion 2 that is in contact with the road surface is provided on the outer side in the tire radial direction of the circumferential reinforcing layer 11.

[Configuration of turbulent ridges]
For the inner turbulence generation as shown in FIG. 1 and FIG. 2 on the inner side in the tire radial direction with the tire maximum width position on the surface of the tire side portion 3 (one-dot broken line shown in FIG. 1, point A shown in FIG. 2) The ridge 20 is projected. Further, a plurality of outer turbulent flow generating ridges 21 are provided on the outer side in the tire radial direction at the tire maximum width position on the surface of the tire side portion 3 as shown in FIGS. 1 and 2.

  The inner turbulent flow generating ridges 20 and the outer turbulent flow generating ridges 21 extend along the tire radial direction and are formed intermittently (equally spaced in the tire circumferential direction) along the tire circumferential direction. Yes. In the present embodiment, the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 have a rectangular cross-sectional shape, but the cross-sectional shape may be a polygonal shape or a curved shape. May be. The heights of the inner turbulent flow generating ridges 20 and the outer turbulent flow generating ridges 21 from the surface of the tire side portion 3 are as shown in FIG. Are set to be higher than the heights h2 and h4 from the tire side 3 surface of the tire radial direction outer ends 20A and 21A.

  The height h, the pitch p, and the width w, where h is the height, p is the pitch, and w is the width of the central portion in the extending direction of the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21. Is set so as to satisfy the relationship of 1.0 ≦ p / h ≦ 50.0 and 1.0 ≦ (p−w) /w≦100.0. Further, the ratio value (p / h) of the pitch p and the height h is preferably set within a range of 2.0 ≦ p / h ≦ 24.0, more preferably 10.0 ≦ p / h ≦ 20.0. By doing so, the heat transfer coefficient of the tire side part 3 surface can be improved more. In the present specification, “pitch” means a distance between points obtained by dividing the width of the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 at the center in the extending direction.

  In this embodiment, it is assumed that the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 are formed discontinuously in the tire radial direction as shown in FIG. 3, but as shown in FIG. The inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 may be continuously connected in the tire radial direction at the tire maximum width position on the surface of the tire side portion 3. Further, as shown in FIG. 5, the tire radial inner end 20 </ b> B of the inner turbulent flow generating ridge 20 may be connected to the tire radial inner end 20 </ b> B of another inner turbulent flow generating ridge 20.

  In this embodiment, it is assumed that the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 have the same pitch. However, as shown in FIG. The pitch is made larger than the pitch of the outer turbulent flow generating ridges 21 or the pitch of the inner turbulent flow generating ridges 20 is made smaller than the pitch of the outer turbulent flow generating ridges 21 as shown in FIG. Or you may. When the pitch of the inner turbulent flow generating ridges 20 is made smaller than the pitch of the outer turbulent flow generating ridges 21 as shown in FIG. 6B, the tire maximum width position on the surface of the tire side portion 3 is the boundary. Since the amount of air contacting the outer side in the tire radial direction can be increased, the cooling effect can be enhanced.

  Similarly, when the pitch of the inner turbulent flow generating ridges 20 is different from the pitch of the outer turbulent flow generating ridges 21, as shown in FIG. The end portion 20B may be connected to the tire radial direction inner end portion 20B of the other inner turbulent flow generating ridge 20, or the inner turbulent flow generating ridge 20 and the outer portion as shown in FIG. 7B. The turbulent flow generating ridge 21 may be continuously connected at the position of the tire maximum width on the surface of the tire side portion 3 (reference numeral 22).

  In the present embodiment, the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 are formed in parallel to the tire radial direction, as shown in FIGS. 8A and 8B. In addition, an angle θ with respect to the tire radial direction may be provided. Further, the angle θ formed with the tire radial direction may be constant in the tire circumferential direction or may be changed within the tire circumferential direction. Similarly, the pitch, height, and width of the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 may not be constant in the tire radial direction and the tire circumferential direction.

  The angle θ formed by the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 with respect to the tire radial direction is preferably in the range of −70 ° ≦ θ ≦ 70 °. Since the run-flat tire 1 is a rotating body, the air flow on the surface of the tire side portion 3 is slight but is directed outward in the radial direction by centrifugal force. In order to reduce the stagnation part of the air on the back side with respect to the inflow of air from the inner turbulent flow generating ridge 20 and the outer turbulent flow generating ridge 21 and to improve the cooling effect, in the above angle range with respect to the radial direction. It is preferable to incline.

[Mechanism of turbulent flow generation]
In the run-flat tire 1 having such a configuration, as shown in FIG. 9, the tire side portion 3 in which no ridges (inner turbulent flow generation ridges 20 and outer turbulent flow generation ridges 21) are formed. The air flow S1 that has been in contact is separated from the tire side portion 3 by the protrusions as it rotates and gets over the protrusions. At this time, a portion (region) S <b> 2 in which the air flow stays is generated on the back side of the protrusion. Then, the air flow S1 reattaches to the bottom between the next protrusion and is peeled again by the next protrusion. At this time, a portion (region) S3 in which the air flow stays is generated between the air flow S1 and the next protrusion.

  In general, when the run-flat tire 1 is rotating, the tire circumferential speed inside the tire radial direction is slower than the tire circumferential speed outside the tire radial direction, and the pressure inside the tire radial direction is outside the tire radial direction. Higher than pressure. For this reason, as shown in FIG. 10A, the air flow S1 in contact with the tire side portion 3 flows in a direction in which the flow from the inner side in the tire radial direction to the outer side in the tire radial direction and the flow in the tire circumferential direction are combined. Become.

  In addition, although the inclination of the direction of the air flow S1 is proportional to the speed in the tire circumferential direction, the surface of the tire side portion 3 has a curvature, so the air flow in the tire radial direction inside the tire radial direction with the tire maximum width position as a boundary. Tends to peel off at the maximum tire width position. For this reason, on the outer side in the tire radial direction with the tire maximum width position as a boundary, the air flow from the inner side in the tire radial direction to the outer side in the tire radial direction becomes weak, and the air flow in the tire circumferential direction becomes strong, so that FIG. ), The inclination of the direction of the air flow S1 decreases rapidly.

  Therefore, in the run-flat tire 1 of the present embodiment, as described above, the height of the inner end portion 20B in the tire radial direction of the inner turbulent flow generation protrusion 20 that protrudes inward in the tire radial direction with the tire maximum width position as a boundary. It was made higher than the height of the tire radial direction outer end 20A. According to such a configuration, since the flow in the tire circumferential direction becomes faster toward the outer side in the tire radial direction, the air flow S1 is prevented from being separated at the tire maximum width position, and the amount of air that contacts the surface of the tire side 3 Can be more. Thereby, a more efficient cooling effect can be realized.

  Furthermore, in the run flat tire 1 of this embodiment, as described above, the height of the tire radial direction inner end portion 21B of the outer turbulent flow generation protrusion 21 protruding outward in the tire radial direction with the tire maximum width position as a boundary is set. It was made higher than the height of the tire radial direction outer end 20A. According to such a configuration, it is possible to suppress separation of the air flow S1 on the outer side in the tire radial direction, and to increase the amount of air that contacts the tire side 3 surface. Thereby, a more efficient cooling effect can be realized.

〔Example〕
Hereinafter, the present invention will be specifically described based on examples.

[Example 1]
In Example 1, the values of parameter p / h, parameter (p−w) / w, width w, and angle θ are set to 15, 29, 1 mm, and 0 °, respectively, and heights h1, h2, h3, and h4 are set. By setting the values to 2.0 mm, 1.8 mm, 2.0 mm, and 1.8 mm, respectively, the run-flat tire of Example 1 having a tire size of 285 / 50R20 and a rim of use: 8.0JJ × 20 was obtained. .

[Example 2]
In Example 2, the run of Example 2 was performed in the same manner as Example 1 except that the values of heights h1, h2, h3, and h4 were set to 2.0 mm, 1.0 mm, 2.0 mm, and 1.0 mm, respectively. I got a flat tire.

Example 3
In Example 3, the run of Example 3 was performed in the same manner as Example 1 except that the values of heights h1, h2, h3, and h4 were set to 2.0 mm, 0.8 mm, 2.0 mm, and 0.8 mm, respectively. I got a flat tire.

[Comparative Example]
In the comparative example, a protrusion having a constant height (2 mm) in the tire radial direction is provided, and parameters p / h, parameter (p−w) / w, width w, and angle θ are set to 15, 29, respectively. , 1 mm, and 0 °, a comparative run-flat tire was obtained.

[Durable drum test]
Durability drum tests (internal pressure: 0 kPa, load: 9.8 kN, speed: 90 km / h) were performed on Examples 1 to 3 and comparative example run flat tires. The test results are shown in Table 1 below. The test results are shown as values obtained by indexing the endurance distance until the failure occurs.

[Evaluation]
As shown in Table 1, the durability of the run flat tires of Examples 1 to 3 was higher than the durability of the run flat tire of the comparative example. From this, it is found that by forming the inner turbulent flow generating ridge and the outer turbulent flow generating ridge according to the present invention on the surface of the tire side portion, it is possible to enhance the cooling effect and consequently improve the durability of the tire. It was done.

  Next, FIG. 11 and FIG. 12 show the results of obtaining the heat transfer coefficient using the turbulent flow generation ridges 20 with different p / h and (p−w) / w. The vertical axis of the graphs of FIGS. 11 and 12 is obtained by applying a constant voltage to the heater attached to the tire surface to generate a certain amount of heat and measuring the temperature of the tire surface when the tire is rotated. Heat transfer coefficient. That is, this large heat transfer coefficient indicates that the cooling effect is high. Here, the heat transfer coefficient of a run flat tire having no turbulent flow generating ridge is set to 100. This heat transfer coefficient measurement test was performed under the following conditions.

Tire size: 285 / 50R20
Rim used: 8.0JJ × 20
Internal pressure: 0 kPa
Load: 0.5kN
Speed: 90km / h
FIG. 11 is a diagram showing the relationship between the durability (p / h) and the ratio value (p / h) between the pitch p and the height h of the inner turbulent flow generating ridge and the outer turbulent flow generating ridge. Is 1.0 or more and 50.0 or less, it has shown that the heat transfer rate is increasing. From FIG. 11, in the inner turbulent flow generating ridge and the outer turbulent flow generating ridge, the value of p / h is preferably in the range of 1.0 ≦ p / h ≦ 50.0, preferably 2.0 ≦ p / It has been found that a range of h ≦ 24.0, more preferably a range of 10.0 ≦ p / h ≦ 20.0, is good.

  FIG. 12 is a diagram showing the relationship between the parameter (pw) / w and the heat transfer coefficient, and the value of the parameter (pw) / w is 1.0 ≦ (pw) / w ≦ 100. 0.0, preferably 4.0 ≦ (p−w) /w≦39.0 satisfies the relationship of increasing the heat transfer coefficient.

  FIG. 13 shows that the angle θ in the extending direction of the inner turbulent flow generating ridge and the outer turbulent flow generating ridge with respect to the tire radial direction is preferably in the range of 0 ° to 70 °. It is considered that the same heat transfer coefficient is exhibited even within the range of 0 ° to 0 °.

  As mentioned above, although the embodiment to which the invention made by the present inventor is applied has been described, the present invention is not limited by the description and the drawings that form part of the disclosure of the present invention according to this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above embodiments are all included in the scope of the present invention.

1 is a side 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 in the II-II cross section of FIG. It is a principal part perspective view which shows the protrusion for inner turbulent flow generation | occurrence | production and the protrusion for outer turbulent flow generation of the run flat tire used as embodiment of this invention. It is a principal part perspective view which shows the modification of the protrusion for inner side turbulent flow shown in FIG. 3, and the protrusion for outer side turbulent flow generation. It is a principal part perspective view which shows the modification of the protrusion for inner side turbulent flow shown in FIG. 3, and the protrusion for outer side turbulent flow generation. It is a side view of the modification of the run flat tire used as the embodiment of the present invention. It is a side view of the modification of the run flat tire used as the embodiment of the present invention. It is a side view of the modification of the run flat tire used as the embodiment of the present invention. It is explanatory drawing which shows the turbulent flow generation mechanism of the state which cut | disconnected the inner turbulent flow generation protrusion and the outer turbulent flow generation protrusion in the tire circumferential direction. It is a figure for demonstrating the direction of the airflow of a tire radial direction inner side and a tire radial direction outer side on the boundary of a tire maximum width position. It is a figure which shows the relationship between parameter p / h and a heat transfer rate. It is a figure which shows the relationship between parameter (pw) / w and a heat transfer rate. It is a figure which shows the relationship between the angle with respect to the tire radial direction of the inner turbulent flow generation protrusion and the outer turbulent flow generation protrusion and the heat transfer coefficient.

Explanation of symbols

1: Run flat tire 3: Tire side portion 4: Bead portion 8: Side wall reinforcing layer 20: Inner turbulent flow generating ridge 20A, 21A: Outer end portion 20B, 21B: Inner end portion 21: For generating outer turbulent flow Ridge

Claims (7)

A plurality of inner turbulent flow generations extending along the tire radial direction and spaced apart along the tire circumferential direction on the inner side in the tire radial direction with the tire maximum width position on the surface of the tire side portion as a boundary Ridges are formed,
A plurality of outer turbulence generations extending along the tire radial direction and spaced apart along the tire circumferential direction on the outer side in the tire radial direction with respect to the tire maximum width position on the surface of the tire side portion Ridges are formed,
The height of the inner turbulent flow generating ridge and the outer turbulent flow generating ridge from the tire side portion surface is the tire radial inner end height from the tire side portion surface. A pneumatic tire characterized by being set to be higher than the height of the portion from the surface of the tire side portion.   2. The pneumatic tire according to claim 1, wherein a height of a tire radial inner end of the inner turbulent flow generating ridge is h <b> 1, and a height of a tire radial outer end of the inner turbulent flow generating ridge is set. Where h2 is the height of the inner radial end of the outer turbulent flow generating ridge h3, and h4 is the height of the outer radial rim end of the outer turbulent generating ridge. A pneumatic tire characterized by h1, height h2, height h3, and height h4 satisfying a relationship of 0.5h1 ≦ h2 ≦ 0.9h1 and 0.5h3 ≦ h4 ≦ 0.9h3.   3. The pneumatic tire according to claim 1, wherein the height of the central portion in the extending direction of the inner turbulent flow generating ridge and the outer turbulent flow generating ridge is h, the pitch is p, and the width is When w, the height h, the pitch p, and the width w satisfy the relationship of 1.0 ≦ p / h ≦ 50.0 and 1.0 ≦ (p−w) /w≦100.0. A pneumatic tire characterized by that.   4. The pneumatic tire according to claim 1, wherein a pitch of the inner turbulent flow generating ridge is smaller than a pitch of the outer turbulent flow generating ridge. 5. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 4, wherein the inner turbulent flow generating ridge and the outer turbulent flow generating ridge are continuously integrated along a tire radial direction. A pneumatic tire characterized in that it is formed.   The pneumatic tire according to any one of claims 1 to 5, wherein the tire side portion includes a reinforcing rubber having a crescent-shaped cross section in the tire radial direction.   The pneumatic tire according to any one of claims 1 to 6, wherein the pneumatic tire is a run-flat tire.

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