JP2009029370A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire with high temperature reduction effect of a tire side part capable of suppressing breakage of a turbulence flow generation protrusion. <P>SOLUTION: A plurality of turbulence flow generation protrusions 20 extended along in a tire radial direction r and formed along a tire circumferential direction with a gap are formed on a surface of the tire side part 3, and an outer end part 20A in the tire radial direction r of the turbulence flow generation protrusion 20 is arranged in a ground-contactable specification area A of the tire side part 2. A portion positioned in the ground-contactable specification area A is formed such that height is gradually reduced toward the outer end part 20A. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire having a cooling function provided with a highly durable turbulent flow generating ridge.

  In general, an increase in the tire temperature of a pneumatic tire is not preferable from the viewpoint of durability because it promotes a change over time such as a change in material properties, or causes a tread breakage during high-speed running. In particular, in a run flat tire during puncture traveling (when traveling at an internal pressure of 0 kPa) in a passenger car, it is a major issue to reduce the tire temperature in order to improve durability. 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 this tire temperature reducing means, by forming ridges for generating turbulent flow along the tire radial direction in the tire side portion, the generation of turbulent flow on the tire surface is promoted and the cooling effect is improved. Yes (see 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 dissipation area and aiming for the heat dissipation effect. .
International Publication No. 2007/032405 Pamphlet

  Usually, the region where the road surface is side-grounded in a pneumatic tire is approximately 20 mm to 40 mm inward in the radial direction from the tread surface. From the viewpoint of reducing the temperature of the tire side portion, it is preferable that the turbulent flow generating ridge is also formed on the tire side portion at the outer side in the tire radial direction. However, when the turbulent flow generating ridge is formed on the outer surface of the tire side portion, the following problems occur. That is, when a large lateral force is applied when the vehicle suddenly bends a curve, the portion near the tread surface on the outer side in the tire radial direction of the tire side portion contacts the road surface, and the turbulent flow generating ridge is destroyed by the road surface. This causes a malfunction. As this measure, it is conceivable that the ridge for generating turbulent flow is not formed in the tire radial direction outer portion of the tire side portion, but there is a problem that the temperature reduction effect by the ridge for generating turbulent flow is lowered. .

  Therefore, an object of the present invention is to provide a pneumatic tire that has a high temperature reduction effect at the tire side portion and can suppress the destruction of the ridge for generating turbulent flow.

  As a result of diligent research focusing on the above-mentioned problems, when the turbulent flow generating ridge is disposed in the ground contactable prescribed region from the position of the tread surface to the inner position in the tire radial direction of about 40 mm, the turbulent flow generating ridge It has been found that by tilting the outer end of the tire in the radial direction so as to gradually decrease, the ridge for generating turbulent flow is not destroyed even at the time of side contact, and the cooling effect can be maintained. . The reason for this is that if the height of the turbulent flow generating ridge is low in the groundable regulation region, the turbulent flow generating ridge becomes difficult to contact the road surface. Since it is low, the bending rigidity is high and the turbulent flow generating ridge is not easily deformed. For this reason, the stress value applied to the base portion (root portion) in the vicinity of the surface of the tire side portion of the turbulent flow generating ridge becomes small, and the turbulent flow generating ridge is less likely to fail.

  According to the first aspect of the present invention, a plurality of turbulent flow generating ridges are formed on the surface of the tire side portion so as to extend along the tire radial direction and be spaced apart along the tire circumferential direction. In the pneumatic tire, the outer end of the turbulent flow generating ridge in the tire radial direction is disposed in the groundable prescribed region of the tire side portion, and the portion located in the groundable prescribed region is the outer end The gist is that the height is gradually reduced toward the portion.

  Here, the ground contactable specified region is a region from the tread surface (surface perpendicular to the tire radial direction passing through the surface of the maximum tread portion) to a predetermined distance inside the tire radial direction. Specifically, from the tread surface It is preferable to be disposed in the tire surface region at a distance of up to 40 mm inward in the tire radial direction, and the outer end portion is preferably located in the tire radial direction inner side than the 20 mm position from the tread surface.

  The invention according to claim 2 is the pneumatic tire according to claim 1, characterized in that the ground contactable defining region is defined when the tire has a proper tire internal pressure in a maximum tread state.

  Invention of Claim 3 is the pneumatic tire described in Claim 1 or Claim 2, Comprising: The boundary located in the tire radial direction innermost side from the tread surface of the contactable regulation area | region in the protrusion for turbulent flow generation | occurrence | production When the height of the portion is h1, and the height h2 of the outer end portion is set, the height h3 at the intermediate position between the boundary portion and the outer end portion is h3 = 0.4 to 0.7 ×. (H1−h2) + h2 is satisfied.

  In this way, by defining the gauge distribution in which the outer portion in the tire radial direction gradually decreases only within the groundable prescribed region in the turbulent flow generating ridge, the cooling effect by the turbulent flow generating ridge and the turbulent flow generating It is possible to achieve both the durability of the ridge. If the height h3 at the intermediate position is lower than the above range, the height of the turbulent flow generating ridge within the groundable specified region cannot be secured, and the temperature reduction effect is reduced. The flow generating ridges are easily destroyed.

  A fourth aspect of the present invention is the pneumatic tire according to any one of the first to third aspects, wherein the plurality of turbulent flow generating ridges are arranged at equal intervals and adjacent to each other. When the distance p between positions where the maximum height h of the ridges for generating turbulent flow is defined, there is a relationship of 1.0 ≦ p / h ≦ 50.0, and 1.0 ≦ (p−w) The relationship of /w≦100.0 is satisfied.

  The invention described in claim 5 is the invention described in claim 4, wherein the height of the turbulent flow generating ridge at the maximum height position is 1 to 5 mm.

  Invention of Claim 6 is a pneumatic tire as described in any one of Claim 1 thru | or 5, Comprising: The part arrange | positioned in the said earthing | grounding prescribed | regulated area | region in the said ridge for turbulent flow generation | occurrence | production Is characterized by being 2.5 mm or less in height.

  Considering the possibility that the turbulent flow generating ridge may be broken by side grounding during cornering, the above condition is preferable in order to smoothly reduce the gauge gradually.

  Invention of Claim 7 is a pneumatic tire as described in any one of Claim 1 thru | or 6, Comprising: The tire side part is equipped with the reinforcing rubber whose cross-sectional shape of a tire radial direction is a crescent shape. It is characterized by that.

  According to the present invention, the portion located in the groundable prescribed region of the tire side portion in the turbulent flow generating ridge is formed so that the height gradually decreases toward the outer end portion. Even when a large lateral force is applied when the vehicle suddenly bends a curve, the turbulent flow generating ridge can be prevented from being broken without contacting the road surface. Even when the turbulent flow generating ridge contacts the road surface, the turbulent flow generating ridge has a low height, so the bending rigidity is high, and the turbulent flow generating ridge is the root (lower part) of the turbulent flow generating ridge, which is the starting point of the failure The applied stress value is reduced, and the destruction of the turbulent flow generating ridge can be suppressed.

  Further, according to the present invention, the height of the boundary portion located on the innermost side in the tire radial direction from the tread surface of the contactable prescribed region in the turbulent flow generating ridge is defined as h1, and the height of the outer end portion is defined as h2. Sometimes, the height h3 at an intermediate position between the boundary portion and the outer end portion satisfies h3 = 0.4 to 0.7 × (h1−h2) + h2, and thus a turbulent flow generating ridge. It can suppress that the outer side edge part of grounds.

  According to the present invention, there is a relationship of 1.0 ≦ p / h ≦ 50.0 when the distance p between the maximum height positions of the adjacent turbulent flow generating ridges is 1.0. Since the relationship of ≦ (p−w) /w≦100.0 is satisfied, the cooling effect due to the generation of turbulent flow can be enhanced.

  ADVANTAGE OF THE INVENTION According to this invention, there exists an effect which improves the cooling effect of the tire side part of a run flat tire, and also improves the durability of the protrusion for turbulent flow generation.

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

  1 to 4 show a run flat tire 1 as a pneumatic tire according to an embodiment of the present invention and a portion thereof. 1 is a side view of the run-flat tire 1, FIG. 2 is a cross-sectional view of the main part showing the II-II cross section of FIG. 1, and FIG. 3 is a perspective view of the main part showing the outer end in the tire radial direction FIG. 4 is an explanatory cross-sectional view of a turbulent flow generating ridge on the tire side surface of a run-flat tire cut in the tire circumferential direction.

<Schematic configuration of run-flat tire>
As shown in FIGS. 1 and 2, the run-flat tire 1 includes a tread portion 2 that comes into contact with the road surface, tire side portions 3 on both sides of the tire, and beads provided along the opening edges of the respective tire side portions 3. And a portion 4. As shown in FIG. 1, a plurality of turbulent flow generating ridges 20 project intermittently (equally spaced in the tire circumferential direction) along the circumferential direction on the outer surface of the tire side portion 3. .

  As shown in FIG. 2, 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. Specifically, a steel cord or the like is used as the bead core 6A.

  As shown in FIG. 2, the run flat tire 1 has a carcass layer 7 that serves as a skeleton of the tire. 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.

  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. The tread portion 2 that contacts the road surface is provided on the outer side in the tire radial direction of the circumferential reinforcing layer 11.

<Structure of turbulent ridges>
In the run-flat tire 1 having the tire side portion 3 provided with the sidewall reinforcing layer 8 made of crescent-shaped reinforcing rubber as in the present embodiment, reducing the temperature of the tire side portion 3 improves the durability. Effective from the viewpoint.

  Therefore, the turbulent flow generation ridge 20 is formed to be elongated in the tire side portion 3 along the tire radial direction. The cross section in the tire circumferential direction of the turbulent flow generating ridge 20 is formed in a rectangular shape.

  As shown in FIG. 2, the turbulent flow generation ridge 20 is formed within the range of the cross-sectional height (H) from the base line of the rim (not shown) to the tread surface.

  The outer end 20A in the tire radial direction of the turbulent flow generation ridge 20 is disposed so as to be located within a predetermined range of the groundable prescribed region A. The ground contactable regulation area A is an area defined when the run-flat tire 1 is in the maximum tread and has an appropriate tire internal pressure. In a normal pneumatic tire for a passenger car, the tread surface is inward in the tire radial direction. The range is up to 40 mm. In addition, the outer end 20 </ b> A is arranged so as not to enter the normal groundable area B. This normal ground contactable region B is a region where the run flat tire 1 is grounded on the road surface when a large lateral force is not applied, and is a region from the tread surface to the inner side in the tire radial direction up to a distance of 20 mm. is there.

  Further, as shown in FIG. 3, a portion of the turbulent flow generation ridge 20 that is located in the groundable prescribed region A is set so that the height gradually decreases toward the outer end 20 </ b> A. As shown in FIG. 3, the height of the turbulent flow generating ridge 20 at the innermost position in the tire radial direction of the ground contactable defined region A is h1, the height of the outer end 20A is h2, and the height at these intermediate positions is When h3 is set to h3, it is set to satisfy h3 = 0.4 to 0.7 × (h1−h2) + h2. In addition, the height of the portion of the turbulent flow generation ridge 20 arranged in the groundable prescribed region A is set to 2.5 mm or less.

  On the other hand, the inner end 20 </ b> B in the tire radial direction of the turbulent flow generation ridge 20 is arranged to be located on the outer side in the tire radial direction than the bead portion 4. The inner end portion 20B is not gradually lowered like the outer end portion 20A described above, but is equal to or slightly lower than the center height h of the turbulent flow generation projection 20. Is formed.

  In the present embodiment, as shown in FIG. 4, the turbulent flow generating ridges 20 are set to a predetermined interval p, and the height h and the width w of the turbulent flow generating ridges 20 are set to the same dimensions. ing. In addition, the said space | interval p is taken as the distance between the points which equally divided the width | variety of the tire circumferential direction in the center part of the extension direction of the protrusion 20 for turbulent flow generation adjacent to each other. The height h is the height of the portion located in the center in the extending direction of the turbulent flow generation projection 20. The width w is the width of the portion located in the center in the extending direction of the turbulent flow generation ridge 20.

Here, in the ridge 20 for generating turbulent flow, there is a relationship of 1.0 ≦ p / h ≦ 50.0 between the height h, the interval p, and the width w, and 1.0 ≦ ( p−w) /w≦100.0 is set to be satisfied. Preferably, the value (p / h) of the ratio between the distance p and the height h of the turbulent flow generating ridge 20 is 2.0 ≦ p / h ≦ 24.0, more preferably 10.0 ≦ p / h. ≦ 20.0
It is prescribed in the range. The height h is set in a range of 1 ≦ h ≦ 5 mm. The width w is set in a range of 0.5 ≦ w ≦ 5 mm.

  As described above, when the air flow (turbulent flow) defined by p / h is excessively finely divided, that is, when the interval p is narrowed, air flows in the portion between the turbulent flow generating ridges 20. If the flow p does not enter and the interval p is too wide, it will be equivalent to the case where the turbulent flow generation projection 20 is not shaped, so it is preferable to set the numerical value range.

  Note that (p−w) / w represents the ratio of the width w of the protruding portion to the interval p, and if this is too small, the surface area of the turbulent flow generating ridge with respect to the area of the surface on which cooling is desired to be improved It is the same as that the ratio of becomes equal. The turbulent flow generating ridge 20 is made of rubber, and the cooling improvement effect due to the increase in surface area cannot be expected so much. Therefore, the minimum value of (p−w) / w is defined as 1.0. (P−w) / w is set in a range of 1.0 ≦ (p−w) /w≦100.0.

  In the present embodiment, the occurrence of deterioration during puncture traveling (when traveling at an internal pressure of 0 kPa) is more likely to occur in the tire side portion 3 than in other portions. By providing the above, the cooling of the tire side portion 3 can be promoted by the turbulent air flow generated by the turbulent flow generation projection 20. This is because the rubber constituting the tire is a material with poor thermal conductivity, so rather than expanding the heat dissipation area and promoting heat dissipation, the generation of turbulence is promoted and the turbulent flow is directly applied to the tire side part. This is because the cooling effect due to is increased. At this time, the outer end portion 20A of the turbulent flow generating ridge 20 formed in the groundable prescribed region A is likely to come into contact with the road surface, but in this case also, the turbulent flow generating ridge 20 is broken. While suppressing this, the cooling effect can be maintained.

  Next, the mechanism of turbulent flow generation will be described with reference to FIG. With the rotation of the run-flat tire 1, the air flow S <b> 1 that has been in contact with the tire side portion 3 where the turbulent flow generating ridge 20 is not formed is separated from the tire side portion 3 by the turbulent flow generating ridge 20. Over the ridge 20 for generating turbulent flow. At this time, a portion (region) S <b> 2 in which the air flow stays is formed on the back side of the turbulent flow generation ridge 20. Then, the air flow S <b> 1 is reattached to the bottom portion between the next turbulent flow generation ridge 20 and is peeled again by the next turbulent flow generation ridge 20. At this time, a portion (area) S3 in which the air flow stays is generated between the air flow S1 and the next turbulent flow generation projection 20 for separation again. Here, it is considered that increasing the velocity gradient (velocity) on the region in contact with the turbulent flow S1 is advantageous for increasing the cooling rate. Such a turbulent flow generation mechanism is the same at the outer end 20A in the tire radial direction of the turbulent flow generating ridge 20, and the gauge distribution on the outer end 20A side is defined as in the present embodiment. By doing so, it becomes possible to suppress the destruction of the turbulent flow generating ridge 20 without significantly suppressing the turbulent flow generating action.

  Further, in the run flat tire 1 of the present embodiment, the turbulent flow generating ridge 20 has a top portion (edge portion) at an end portion on the inner side in the tire radial direction, so that the air flow separated from the edge portion turns. However, it is presumed to flow in the direction in which the centrifugal force acts.

(Example)
Next, examples will be described. In the conventional example, the comparative example 1, and the examples 1 to 6, the endurance drum test was performed under the following conditions. The results of the durability drum test (durability evaluation) are shown in Table 1 below, which is an index of the durability distance until the failure occurs.

  The conventional example is a run flat tire without the turbulent flow generating ridge 20, and the comparative example is a run flat tire formed so that the height of the outer end 20A of the turbulent flow generating ridge 20 does not gradually decrease. In Examples 1 to 6 and Comparative Example, p / h is set to 12. In Examples 1 to 6 and the comparative example, the outer end 20A is arranged at a position 30 mm from the tread surface. The ground contactable defined area A was defined as an area from the tread surface to the position 40 mm inward in the tire radial direction. The height of the outer end 20A was 2 mm in the comparative example, and 0 mm or 0.5 mm in the examples 1 to 6. The height h3 at the intermediate position was 2 mm in the comparative example and 0.8 mm to 1.75 mm in Examples 1-6. The value of (h3-h2) / (h1-h2) was 0 in the comparative example and 0.2-0.8 in Examples 1-6. The maximum height h of the turbulent flow generation ridge 20 was set to 2.0 mm in Example 3 and 4.5 mm in Example 6, and was set to 2.0 mm in other cases.

  In addition, the setting conditions of a run flat tire are as follows.

Tire size: 285 / 50R20
Rim used: 8JJ × 20
(Durability test)
Internal pressure: 0 kPa
Load: 9.8kN
Speed: 90km / h
Under such conditions, the durability distance until failure in the durability drum test was indexed.

(Side ground test)
Internal pressure: 150 kPa (when used at a slightly low internal pressure)
Load: 10.3kN
S. A. Running at 6 ° and confirming the state of side ground contact Under these conditions, it was judged whether or not the turbulent flow generating ridge was broken.

  As shown in Table 1 above, the conventional example had the lowest durability value of 56. This is presumably because the conventional example does not have a ridge for generating a turbulent flow, so that the cooling effect of the tire side portion is low and the durability distance until failure occurs is short. Further, in the durability test, the comparative example in which the height h2 of the outer end 20A is not low has a high cooling effect and has high durability. However, whether or not there is a failure in the turbulent flow generating ridge in the side grounding test, that is, the cornering running test, is a failure (destruction) over the entire circumference.

  In comparison with the conventional example and the comparative example, Examples 1 to 6, in which the height of the outer end 20A of the turbulent flow generating ridge 20 gradually decreases, have high durability by a durability test, and also generate turbulent flow. The occurrence of breakage of the projecting ridge 20 was only slightly seen in the examples. This is because the height is gradually reduced toward the outer end portion 20A of the portion within the ground contactable prescribed region A (region from the tread surface to 40 mm inward in the tire radial direction). While the destruction of the strip 20 is suppressed, the cooling effect by the turbulent flow generation projection 20 is also exhibited. In particular, the value of (h3-h2) / (h1-h2) is preferably set to 0.4 to 0.7.

  Next, FIG. 5 and FIG. 6 show the results of obtaining the heat transfer coefficient using the turbulent flow generating ridges 20 with different p / h and (p−w) / w. The vertical axis of the graphs of FIGS. 5 and 6 was 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 was rotated. Heat transfer coefficient. That is, this large heat transfer coefficient indicates that the cooling effect is high. Here, the heat transfer coefficient of the run flat tire which does not have the turbulent flow generating ridge 20 is set to 100.

  This heat transfer coefficient measurement test was performed under the following conditions.

Tire size: 285 / 50R20
Rim used: 8JJ × 20
Internal pressure: 0 kPa
Load: 0.5kN
Speed: 90km / h
FIG. 5 is a diagram showing the relationship between the ratio (p / h) of the ratio (p / h) between the interval (p) and the height (h) of the turbulent flow generation ridge 20 and p / h is 1. It shows that the heat transfer coefficient is increased at 0 or more and 50.0 or less. FIG. 5 shows that the heat transfer rate is better and the durability is higher when p / h is in the range of 2.0 to 24.0. For this reason, in the uneven part for generating turbulent flow, the range of 1.0 ≦ p / h ≦ 50.0 is good, preferably the range of 2.0 ≦ p / h ≦ 24.0, and more preferably 10.0 ≦ p. A range of p / h ≦ 20.0 is preferable.

  FIG. 6 is a diagram showing the relationship between (p−w) / w and the heat transfer coefficient (measured in the same manner as the above heat transfer coefficient), and 1.0 ≦ (p−w) / w It can be seen that satisfying the relationship of ≦ 100.0, preferably 4.0 ≦ (p−w) /w≦39.0 increases the heat transfer coefficient.

(Other embodiments)
It should not be understood that the descriptions and drawings which form part of the disclosure of the above-described embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in the above-described embodiment, the shape of the turbulent flow generation projection 20 is an elongated rectangular parallelepiped shape, but the cross-sectional shape in the tire circumferential direction may be a trapezoidal shape or other shapes. The turbulent flow generation ridges 20 extend substantially along the tire radial direction, but may of course be arranged so as to have an obliquely inclined angle with respect to the tire radial direction.

1 is a side view of a run flat tire according to an embodiment of the present invention. It is principal part sectional drawing in the II-II cross section of FIG. It is a principal part perspective view which shows the outer side edge part of the protrusion for turbulent flow generation | occurrence | production of the run flat tire which concerns on embodiment of this invention. It is explanatory drawing which shows the turbulent flow generation | occurrence | production mechanism of the state cut | disconnected in the circumferential direction tire tire for turbulent flow generation | occurrence | production. It is a figure which shows the relationship between p / h and a heat transfer rate. It is a figure which shows the relationship between (pw) / w and a heat transfer rate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Run flat tire, 3 ... Tire side part, 4 ... Bead part, 8 ... Side wall reinforcement layer, 20 ... Projection for turbulent flow generation, 20A ... Outer edge part, A ... Specified area | region which can be grounded

Claims (7)

A pneumatic tire in which a plurality of turbulent ridges are formed on the surface of the tire side portion along the tire radial direction and spaced apart along the tire circumferential direction.
The outer end of the turbulent flow generating ridge in the tire radial direction is disposed within a groundable prescribed region of the tire side,
The pneumatic tire is characterized in that a portion located in the groundable prescribed region is formed such that the height gradually decreases toward the outer end portion.   2. The pneumatic tire according to claim 1, wherein the groundable regulation region is defined when the tire pressure is appropriate in a maximum tread state. In the turbulent flow generation ridge, when the height of the boundary portion located on the innermost side in the tire radial direction from the tread surface of the groundable prescribed region is h1, and the height h2 of the outer end portion, the boundary portion And the height h3 at an intermediate position between the outer end portion and
h3 = 0.4-0.7 * (h1-h2) + h2
The pneumatic tire according to claim 1 or 2, wherein the pneumatic tire is satisfied. The plurality of turbulent flow generating ridges are arranged at equal intervals,
When the interval between the positions where the maximum height h of the turbulent flow generating ridges adjacent to each other is p is p,
The relationship of 1.0 ≦ p / h ≦ 50.0 is satisfied, and the relationship of 1.0 ≦ (p−w) /w≦100.0 is satisfied. The pneumatic tire described in any one of the items.   The pneumatic tire according to claim 4, wherein a height of the turbulent flow generation ridge at the maximum height position is 1 to 5 mm.   The height of the part arrange | positioned in the said earth | groundable prescription | regulation area | region in the said protrusion for turbulent flow generation is 2.5 mm or less, It described in any one of Claim 1 thru | or 5 characterized by the above-mentioned. Pneumatic tire.   The pneumatic tire according to any one of claims 1 to 6, wherein the tire side portion includes a reinforcing rubber having a crescent-shaped cross section in a tire radial direction.

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