JP2010269689A - Run-flat tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability during run-flat drive and ride comfort during ordinary drive. <P>SOLUTION: In a run-flat tire 1, a length from a position of a bead 10 to an internal portion Cin in the tire diametrical direction is expressed an a first length SWHin. A length from the position of the bead 10 to an external portion Cout in the tire diametrical direction is expressed as a second length SWHout. The first length SWHin is longer than the second length SWHout. A length in the tire diametrical direction from the position of the bead 10 of the run-flat tire 1 to a maximum thickness D1max of a reinforcing rubber layer 31 is taken as a distance DHin. A length in the tire diametrical direction from the position of the bead 10 to a maximum thickness D2max of a reinforcing rubber layer 32 of the run-flat tire 1 is taken as a distance DHout. The distance DHin is longer than the first length SWHin and longer than the distance DHout from the position of the bead 10 to the reinforcing rubber layer 32. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a run-flat tire including a reinforcing rubber layer that suppresses deformation of a tire when an internal pressure is reduced, on the inner side of a tire side portion.

  In recent years, run-flat tires having a reinforcing rubber layer on the inner side of the tire side portion have become widespread so that the vehicle can run even when the internal pressure of the tire is significantly reduced due to puncture or the like.

  Since the wheel attached to the vehicle has a camber angle, the load due to the load applied to the entire tire is biased. The load imbalance caused by the camber angle is not related to the tire internal pressure. For this reason, in a vehicle equipped with run-flat tires, a load imbalance similar to that during normal running occurs even when running with a reduced internal pressure (hereinafter referred to as run-flat running). The bias in load accelerates the deterioration of one reinforcing rubber layer and lowers the durability. Therefore, the distance and durability that can be run in flat run are determined by the one reinforcing rubber layer.

  On the other hand, in a vehicle in which the camber angle is set, the thickness of the reinforcing rubber layer disposed on one sidewall portion is made thicker than the thickness of the reinforcing rubber layer disposed on the other sidewall portion. A run flat tire is known (for example, Patent Document 1). The run-flat tire disclosed in Patent Document 1 solves the problems caused by the uneven load caused by the camber angle by changing the thickness of the reinforcing rubber layer to change the rigidity.

JP 2006-131117 A (page 4-5, FIG. 1)

  However, the above-described run flat tire has the following problems. Since the thickness of one reinforcing rubber layer of the above-described run flat tire is thicker than the other, the mass of the entire tire increases. Thereby, rolling resistance was high. Further, when the thickness of the reinforcing rubber layer is different on the left and right, a difference in rigidity occurs in the sidewall portion. For this reason, the so-called longitudinal spring constant of the tire is different between the inner side wall portion and the outer side wall portion, so that the riding comfort during normal traveling is reduced.

  Accordingly, the present invention provides a run-flat tire that can improve durability during run-flat running and improve ride comfort during normal running even when mounted on a vehicle with a set camber angle. The purpose is to provide.

  In order to solve the above-described problems, the present invention has the following features. First, the first feature of the present invention is that a carcass layer (carcass layer 12) including a pair of bead portions (bead portion 10) including at least a bead core and a carcass cord (carcass cord 11) locked to the bead portion. A sidewall portion (sidewall portion 21, sidewall portion 22) that forms the tire side surface, and a reinforcing layer having a crescent-shaped cross section along the tread width direction and the tire radial direction inside the sidewall portion A first portion (inner portion Cin) where the carcass layer is farthest in the tread width direction from the tire equator line, and on the opposite side of the tire equator line to the first portion. And the carcass layer has a second portion (outer portion Cout) furthest away from the tire equator line, and the reinforcing layer has one sidewall portion (a sub-portion). A first reinforcing layer (reinforcing rubber layer 31) disposed in the wall portion 21) and a second reinforcing layer (reinforcing rubber layer 32) disposed in the other side wall portion (outer side wall portion 22). A first length (SWHin), which is a length in the tire radial direction from the position of the bead portion to the first portion, in the tire radial direction from the position of the bead portion to the second portion. The first reinforcing layer distance (DHin) that is longer than the second length (SWHout) that is the length and is the length in the tire radial direction from the position of the bead portion to the maximum thickness portion of the first reinforcing layer. Is longer than the first length and longer than the second reinforcing layer distance (DHout) which is the length in the tire radial direction from the position of the bead portion to the maximum thickness portion of the second reinforcing layer. Is the gist.

  According to the present invention, the length in the tire radial direction based on the bead portion of the portion where the carcass layer is farthest in the tread width direction from the tire equator line in the one sidewall portion, in the other sidewall portion, It is longer than the length in the tire radial direction based on the bead portion where the carcass layer is farthest from the tire equator line in the tread width direction.

  Thereby, the curvature of the carcass layer in a portion (referred to as a shoulder portion) that extends from one sidewall portion to the tread portion is reduced. Therefore, at normal internal pressure, the tension of the carcass layer becomes small.

  Further, the curvature of the carcass layer in the portion (referred to as a shoulder portion) that extends from the other sidewall portion to the tread portion is increased. Therefore, the tension of the carcass layer is increased at normal internal pressure.

  Accordingly, during traveling at normal internal pressure, the rigidity on one side wall portion side can be reduced and the rigidity on the other side wall side can be increased.

  Further, the shoulder portion having a small curvature of the carcass layer easily deforms the tire when the internal pressure is reduced. On the other hand, in the run flat tire according to the present invention, the first reinforcing layer distance (DHin) is longer than the second reinforcing layer distance (DHout). That is, on the side of the one side wall portion where the curvature of the carcass layer is small and easily deformed, a portion having the highest rigidity of the reinforcing rubber layer is disposed at a position close to a location where the curvature of the carcass layer is small. Thereby, the effect which prevents a deformation | transformation of a shoulder part in one side wall part rather than the other side wall part is heightened. That is, durability during run-flat traveling is enhanced.

  Therefore, according to the present invention, it is possible to provide a run-flat tire that can improve durability during run-flat running and improve ride comfort during normal running.

  The second feature of the present invention relates to the first feature of the present invention, and is summarized in that the first reinforcing layer and the second reinforcing layer are made of the same material and have the same shape.

  According to the present invention, the balance of rigidity of the entire tire is adjusted by using the first reinforcing layer and the second reinforcing layer that are made of the same material and have the same shape and by changing the position of the tire in the tire. Therefore, it is not necessary to change the design of the reinforcing layer disposed on the inner side and the outer side of the tire, so that the manufacturing cost can be reduced.

  A third feature of the present invention relates to the first feature of the present invention, wherein the length from the tire equator line to the end portion of the tread portion located on the one sidewall portion side in the tread width direction is the tire equator. The gist is that it is longer than the length from the line to the end of the tread portion located on the other sidewall portion side in the tread width direction.

  According to the present invention, the length from the tire equator line to the end portion of the tread portion located on the one sidewall portion side in the tread width direction is the other sidewall portion side from the tire equator line in the tread width direction. By being longer than the length to the end of the tread portion located at, the curvature of the carcass layer in the portion (referred to as a shoulder portion) connected from one sidewall portion to the tread portion is further reduced. For this reason, it is possible to further reduce the rigidity of one side wall portion during traveling at normal internal pressure. In addition, on the one side wall side, the portion having the highest rigidity of the reinforcing rubber layer is disposed at a position closer to a portion where the curvature of the carcass layer is small. For this reason, during traveling when the internal pressure is reduced, one sidewall portion can further increase the rigidity of the inner shoulder portion that is most easily deformed than the other sidewall portion.

  A fourth feature of the present invention relates to the first feature of the present invention, and is summarized in that the one side wall portion is mounted toward the inside of a vehicle in which a negative camber is set. According to the present invention, in a vehicle set as a negative camber, one side wall portion is attached toward the inside of a vehicle that is likely to be subjected to a large load, thereby reducing the inner rigidity during traveling at normal internal pressure. In addition, it is possible to increase the rigidity of the inner shoulder portion that is most easily deformed during traveling when the internal pressure is reduced.

  A fifth feature of the present invention relates to the first feature of the present invention, and is summarized in that the one side wall portion is mounted toward the outside of a vehicle in which a positive camber is set. According to the present invention, in a vehicle set as a positive camber, one side wall portion is mounted toward the outside of the vehicle on which a large load is likely to be applied, thereby reducing the outer rigidity during traveling at normal internal pressure. In addition, the rigidity of the outer shoulder portion that is most easily deformed during traveling when the internal pressure is reduced can be increased.

  According to the features of the present invention, it is possible to provide a run-flat tire that can improve durability during run-flat travel and improve ride comfort during normal travel.

1 is a partial perspective view of a run flat tire according to an embodiment of the present invention. It is sectional drawing of the tire radial direction and tire width direction of the run flat tire which concerns on embodiment of this invention.

  Next, an embodiment of a run flat tire according to the present invention will be described with reference to the drawings. Specifically, (1) configuration of run-flat tire, (2) operation and effect, (3) other embodiments, and (4) evaluation will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. In addition, there may be a case where the dimensional relationships and ratios are different between the drawings.

(1) Configuration of Run Flat Tire FIG. 1 is a partially exploded perspective view including a cross section in the tread width direction of a run flat tire 1 shown as an embodiment of the present invention. FIG. 2 is a cross-sectional view of the run flat tire 1 in the tread width direction. In FIGS. 1 and 2, partial cross-sectional hatching is omitted in order to clarify the position of the carcass and the like.

  The run-flat tire 1 has a pair of bead portions 10 including at least a bead core 10a and a bead filler 10b. Specifically, a steel cord or the like is used for the bead core 10a constituting the bead unit 10.

  The run-flat tire 1 includes one bead portion 10 and a carcass layer 12 that is locked to the bead portion. The carcass layer 12 is folded back from the tire radial inner side to the tire radial outer side around the bead core 10a. The carcass layer 12 is made of the carcass cord 11 and rubber, and forms the skeleton of the run-flat tire 1.

  The run-flat tire 1 has a belt layer 15 having two intersecting belt layers (first belt layer 15a and second belt layer 15b) and at least one additional belt layer 15c. The steel cords constituting the first belt layer 15a and the second belt layer 15b are arranged at a predetermined angle (for example, ± 25 degrees) with respect to the tire equator line CL. A tread portion 16 that contacts the road surface is provided on the outer side in the tire radial direction of the first belt layer 15a, the second belt layer 15b, and the additional belt layer 15c.

  The run flat tire 1 forms the side surface of the tire and includes reinforcing rubber layers 31 and 32 on sidewall portions (sidewall portions 21 and 22) connected to the tread portion 16. The reinforcing rubber layers 31 and 32 are disposed along the tread width direction W and the tire radial direction D of the sidewall portions 21 and 22, and the cross-sectional shape is a crescent shape. The reinforcing rubber layers 31 and 32 support the sidewall portions 21 and 22 when the internal pressure is reduced, thereby reducing the deformation of the sidewall portions 21 and 22. The reinforcing rubber layers 31 and 32 are provided on the inner side in the tread width direction of the carcass layer 12 in the tread width direction sectional view.

  The reinforcing rubber layers 31 and 32 are made of the same material and have the same shape. The maximum value of the thickness of the reinforcing rubber layer 31 of the run flat tire 1 is represented as the maximum thickness D1max. Further, the maximum value of the thickness of the reinforcing rubber layer 32 of the run flat tire 1 is represented as the maximum thickness D2max. In the present embodiment, D1max = D2max.

  An inner liner 18 is provided on the inner side in the tire radial direction of the carcass layer 12 and the reinforcing rubber layers 31 and 32. The inner liner 18 corresponds to a tube and is formed of a highly airtight rubber layer.

  The run-flat tire 1 is located on the inner side Cin where the carcass layer 12 is farthest in the tread width direction W from the tire equator line CL, and on the opposite side of the inner part Cin with respect to the tire equator line CL. And an outer portion Cout farthest from the line CL. In the present embodiment, the inner part Cin constitutes a first part, and the outer part Cout constitutes a second part.

  The reinforcing rubber layer 31 is disposed on one side wall portion 21. In the present embodiment, the sidewall portion 21 is located on the inner side when mounted on a vehicle in which a negative camber is set. The reinforcing rubber layer 32 is disposed on the other sidewall portion 22. In the present embodiment, the sidewall portion 22 is located outside the vehicle on which the negative camber is set. Further, the sidewall portion 21 is located on the outer side when the sidewall portion 21 is attached to a vehicle in which a positive camber is set. The sidewall portion 22 is located inside the vehicle on which the positive camber is set.

  In the run flat tire 1, the length in the tire radial direction from the position of the bead portion 10 to the inner portion Cin is represented as a first length SWHin. The length in the tire radial direction from the position of the bead portion 10 to the outer portion Cout is represented as a second length SWHout. The first length SWHin is longer than the second length SWHout.

  The length in the tire radial direction from the position of the bead portion 10 of the run flat tire 1 to the maximum thickness D1max of the reinforcing rubber layer 31 is defined as a distance DHin. The length in the tire radial direction from the position of the bead portion 10 of the run flat tire 1 to the maximum thickness D2max of the reinforcing rubber layer 32 is defined as a distance DHout. The distance DHin is longer than the first length SWHin and longer than the distance DHout of the reinforcing rubber layer 32 from the position of the bead portion 10. In the embodiment, the distance DHin constitutes the first reinforcing layer distance, and the distance DHout constitutes the second reinforcing layer distance.

  In the run flat tire 1, the length from the tire equator line CL to the end portion of the tread portion 16 located on the side of the inner sidewall portion 21 in the tread width direction W is defined as a tread length TW1. Further, the length from the tire equator line CL to the end of the tread portion 16 located on the outer sidewall portion 22 side in the tread width direction W is defined as a tread length TW2. The tread length TW1 is longer than the tread length TW2. The tread length indicates the length of the tire contact surface in a stationary state when the run-flat tire 1 is mounted on the applicable rim and at a specified air pressure and a specified weight load. Specifically, the length of the tire contact surface at the time of maximum air pressure and maximum load capacity is shown based on the JATMA standard described in the 2000 JATMA YEAR BOOK, with the run-flat tire 1 mounted on a standard rim. In addition, when the TRA standard or the ETRO standard is applied in the place where the run flat tire 1 is used or the place of manufacture, the tread length according to each standard may be used.

  In the run flat tire 1, the length from the tire equator line CL to the inner portion Cin in the tread width direction W is equal to the length from the tire equator line CL to the outer portion Cout in the tread width direction W, and in the tread width direction W, The area S1 of the tread portion located inside the tire equator line CL is larger than the area S2 of the tread portion located outside the tire equator line CL.

(2) Action / Effect According to the run-flat tire 1, the length in the tire radial direction with reference to the bead portion 10 of the inner portion Cin in the sidewall portion 21 attached to the inside of the vehicle set as a negative camber. The first length SWHin is longer than the second length SWHout in the tire radial direction with reference to the bead portion 10 of the outer portion Cout in the sidewall portion 22.

  Thereby, the curvature of the carcass layer 12 in a portion (referred to as a shoulder portion 23) that extends from the sidewall portion 21 to the tread portion 16 is reduced. Therefore, the tension of the carcass layer 12 becomes small at normal internal pressure. Further, the curvature of the carcass layer 12 in a portion (referred to as a shoulder portion 24) that extends from the sidewall portion 22 to the tread portion 16 is increased. Therefore, the tension of the carcass layer 12 is increased at a normal internal pressure.

  In the case of a run flat tire, since the side wall portion is provided with the reinforcing layer, the rigidity of the tire side portion is enhanced. For example, in the case of a vehicle in which a negative camber is set, the load on the inside of the tire becomes large.

  On the other hand, the run-flat tire 1 has a reduced internal rigidity at the inner sidewall portion 21 and a higher rigidity at the outer sidewall portion 22 at normal internal pressure. The load bias applied to the tire by the corners can be absorbed. Therefore, it is possible to improve the riding comfort during normal traveling.

  Further, the shoulder portion 23 having a small curvature of the carcass layer 12 is most easily deformed when the internal pressure is reduced. On the other hand, in the run flat tire 1, the distance DHin is longer than DHout. That is, a portion (maximum thickness D1max) in which the rigidity of the reinforcing rubber layer 31 is highest is disposed on the shoulder portion 23. Thereby, the side wall part 21 is more effective in preventing the shoulder part 23 from being deformed than the side wall part 22.

  In the case of a vehicle in which a negative camber is set, the load on the inside is large regardless of the internal pressure of the tire. In the run-flat tire 1, the effect of preventing the deformation of the shoulder portion 23 is enhanced in the inner side wall portion 21, so that it is possible to absorb the load unevenness during the run-flat travel. That is, durability during run-flat traveling is enhanced.

  Therefore, according to the present invention, it is possible to provide a run-flat tire that can improve durability during run-flat running and improve ride comfort during normal running.

  According to the run-flat tire 1, the balance of rigidity of the entire tire is adjusted by using the reinforcing rubber layers 31, 32 made of the same material and having the same shape, and changing the position in the tire. Therefore, it is not necessary to change the design of the reinforcing layer disposed on the inner side and the outer side of the tire, so that the manufacturing cost can be reduced.

  According to the run-flat tire 1, the tread length TW1, which is the length from the tire equator line CL to the end of the tread portion 16 located on the inner sidewall portion 21 side in the tread width direction W, is the tire equator line CL. Is longer than the tread length TW2 which is the length from the end of the tread portion 16 located on the outer sidewall portion 22 side in the tread width direction W. For this reason, the curvature of the carcass layer 12 in the shoulder portion 23 continuous from the sidewall portion 21 to the tread portion 16 is further reduced. Accordingly, the rigidity on the side wall portion 21 side can be further reduced during traveling at normal internal pressure. Further, on the side wall portion 21 side, the portion having the highest rigidity of the reinforcing rubber layer 31 is disposed at a position closer to a portion where the curvature of the carcass layer 12 is small. For this reason, one side wall part 21 can further increase the rigidity of the inner shoulder part that is most easily deformed than the side wall part 22 during traveling when the internal pressure decreases. Accordingly, it is possible to further improve the durability during the run-flat travel and further improve the riding comfort during the normal travel.

  According to the run-flat tire 1, the area S1 of the tread portion 16 located on the side of the sidewall portion 21 inside the tire equator line CL is larger than the area S2 of the tread portion 16 located on the side of the sidewall portion 22 outside. By doing so, the curvature of the carcass layer 12 in the shoulder portion 23 connected from the sidewall portion 21 to the tread portion 16 is further reduced. Accordingly, it is possible to further improve the durability during the run-flat travel and further improve the riding comfort during the normal travel.

(3) Other Embodiments As described above, the contents of the present invention have been disclosed through the embodiments of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. Should not. From this disclosure, various alternative embodiments and examples will be apparent to those skilled in the art.

  It goes without saying that the present invention includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

(4) Evaluation Riding comfort, handling stability, vertical spring property when a conventional run flat tire is mounted on a vehicle with a negative camber and when a run flat tire according to an embodiment of the present invention is mounted. The durability was compared. The results are shown in Table 1.

Various numerical values of the run flat tire of the comparative example are shown below.
Maximum thickness D1max = 11mm, maximum thickness D2max = 11mm
Distance DHin = Distance DHout = 66mm
1st length SWHin = 2nd length SWHout = 71 mm Tread length TW1 = Tread length TW2 = 120 mm
Various numerical values of the run flat tire of Example 1 are shown below.
Maximum thickness D1max = 11mm, maximum thickness D2max = 11mm
Distance DHin = 71mm, Distance DHout = 66mm
1st length SWHin = 76mm, 2nd length SWHout = 71mm Tread length TW1 = Tread length TW2 = 120mm
Various numerical values of the run flat tire of Example 2 are shown below.
Maximum thickness D1max = 10.5, maximum thickness D2max = 11 mm
Distance DHin = 71mm, Distance DHout = 66mm
1st length SWHin = 76mm, 2nd length SWHout = 71mm Tread length TW1 = 125mm, Tread length TW2 = 120mm
In the run flat tires of Examples 1 and 2, it was found that both the handling stability and the ride comfort were improved. Moreover, the vertical spring property was lowered and the run flat durability was improved.

  DESCRIPTION OF SYMBOLS 1 ... Run flat tire, 10 ... Bead part, 10a ... Bead core, 10b ... Bead filler, 11 ... Carcass cord, 12 ... Carcass layer, 15 ... Belt layer, 15a ... 1st belt layer, 15b ... 2nd belt layer, 15c ... additional belt layer, 16 ... tread part, 18 ... inner liner, 21,22 ... side wall part, 23 ... shoulder part, 24 ... shoulder part, 31,32 ... reinforcing rubber layer, CL ... tire equator line, Cin ... inside Part, Cout ... outer part, D ... tire radial direction, DHin ... distance, DHout ... distance, W ... tread width direction, TW1, TW2 ... tread length, S1, S2 ... tread area,

Claims (5)

A pair of bead portions including at least a bead core;
A carcass layer including a carcass cord locked to the bead portion;
Sidewall portions forming the tire side surfaces;
A run-flat tire provided with a reinforcing layer having a crescent-shaped cross-sectional shape along the tread width direction and the tire radial direction inside the sidewall portion,
A first portion where the carcass layer is farthest away from the tire equator line in the tread width direction;
A carcass layer located opposite to the first part with respect to the tire equator line and the carcass layer having a second part farthest from the tire equator line;
The reinforcing layer is
A first reinforcing layer disposed on one sidewall portion;
A second reinforcing layer disposed on the other sidewall portion,
The first length that is the length in the tire radial direction from the position of the bead portion to the first portion is the second length in the tire radial direction from the position of the bead portion to the second portion. Longer than the length,
The first reinforcing layer distance, which is the length in the tire radial direction from the position of the bead portion to the maximum thickness portion of the first reinforcing layer, is longer than the first length and from the position of the bead portion. A run-flat tire longer than a second reinforcing layer distance which is a length in the tire radial direction up to a maximum thickness portion of the second reinforcing layer.   The run-flat tire according to claim 1, wherein the first reinforcing layer and the second reinforcing layer are made of the same material and have the same shape.   The length from the tire equator line to the end of the tread portion located on the one sidewall portion side in the tread width direction is the length of the tread portion located on the other sidewall portion side in the tread width direction from the tire equator line. The run-flat tire according to claim 1, wherein the run-flat tire is longer than the length to the end.   2. The run flat tire according to claim 1, wherein the one sidewall portion is attached toward an inner side of a vehicle in which a negative camber is set.   The run-flat tire according to claim 1, wherein the one sidewall portion is mounted toward an outside of a vehicle in which a positive camber is set.

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