JP6383264B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire including a rim protector on a sidewall portion.

  In the pneumatic tire, the distance from the road surface of the rim flange becomes smaller as the flatness ratio decreases. Therefore, for example, when the vehicle is brought close to the road shoulder, there is a problem that the rim flange is easily damaged by contacting the curbstone or the like. Therefore, particularly in a super flat tire having a flatness ratio of 55% or less, a rim protector that protects the rim flange by protruding outward in the tire axial direction from the rim flange is formed on the outer surface of the sidewall portion (for example, , See Patent Document 1). This rim protector has an annular shape extending continuously in the tire circumferential direction.

  However, if the rim protector does not hold a sufficient size, it is difficult to achieve the above protection function. Conversely, when the rim protector is enlarged, there is a problem that the rolling resistance performance is lowered due to an increase in the mass of the tire. . Thus, the protection function and the weight reduction of the tire are in a trade-off relationship. In recent years, it is strongly desired to reduce the weight of the tire and improve the rolling resistance performance while exhibiting a high protection effect. .

  In Patent Document 1, it is proposed that the formation positions of the rim protector disposed on one side in the tire axial direction and the rim protector disposed on the other side are different in the tire radial direction. However, this is to prevent the rim protectors from coming into contact with each other when the tires are stacked, and to reduce the tire weight and improve the rolling resistance performance while providing a high protection effect. There is no description about the technology to achieve this.

JP 2009-292428 A

  An object of the present invention is to provide a pneumatic tire capable of reducing the weight of the tire and improving the rolling resistance performance while exhibiting a high protection effect in a super flat tire having a rim protector on a sidewall portion. Yes.

The present invention is a pneumatic tire having a carcass having a carcass main body portion extending from a tread portion to sidewall beads on both sides in the tire axial direction to a bead core of the bead portion and having a flatness ratio of 55% or less,
Each sidewall has a rim protector that continuously extends in the tire circumferential direction with the top most protruding outward in the tire axial direction,
The tire contour line in the tire meridional section is formed by a series of convex arcs in the region from the top to the mold split position that is the boundary between the tread mold for forming the tread portion and the side mold for forming the sidewall portion. With
The outer rim protector outside the vehicle when mounted on the vehicle has a radial height H1 from the bead base line at the top of the rim protector, and the radial height from the bead base line at the top of the rim protector inside the vehicle when mounted on the vehicle. It is characterized by being larger than the height H2.

  In the pneumatic tire according to the present invention, the radial height H0 from the bead base line at the carcass maximum width position where the carcass main body protrudes most outward in the tire axial direction, and the radial height in the outer rim protector. The ratio H1 / H0 to H1 is in the range of 0.65 to 0.83, and the ratio H2 / H0 between the radial height H0 and the radial height H2 in the inner rim protector is 0.52 to 0. .63 is preferable.

In the pneumatic tire according to the present invention, in the outer rim protector, a ratio T1 / L1 between a tire axial distance L1 from the outer surface of the bead portion to the top portion and a thickness T1 from the top portion to the carcass is set. In the range of 0.70 to 0.75,
In the inner rim protector, a ratio T2 / L2 between a tire axial distance L2 from the outer surface of the bead portion to the top portion and a thickness T2 from the top portion to the carcass is in a range of 0.67 to 0.77. Preferably there is.

  In the present application, the dimension of each part of the tire is a value specified in a normal internal pressure state in which the tire is assembled on a normal rim and filled with a normal internal pressure. The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim". The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum air pressure in the case of JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, If it is ETRTO, it means “INFLATION PRESSURE”, but in the case of a passenger car tire, it is 180 kPa.

  As described above, in the present invention, a region from the top of the rim protector to the mold split position is formed by a series of convex arcs in the tire contour. Therefore, in the said area | region, the curvature radius of a tire outline becomes large compared with the curvature radius of a carcass.

  As a result, in the buttress part near the mold split position, the rubber is reduced by bringing the tire contour line closer to the carcass while maintaining the rigidity from the carcass maximum width position to the bead. It becomes possible to do. That is, the cornering performance can be maintained while reducing the weight. In particular, the buttress portion is a portion where the tire is greatly deformed during running, and has a great influence on the rolling resistance. Therefore, rolling resistance performance can be effectively reduced by reducing the weight of the buttress portion. Further, by forming the region with a series of convex arcs, the rubber thickness near the carcass maximum width position is increased, thereby contributing to the improvement of anti-pinch cut resistance.

  Furthermore, in the present invention, in the outer and inner rim protectors, the heights H1 and H2 in the radial direction from the bead base line at each top are made different. In particular, by increasing the radial height H1, the top of the outer rim protector is close to the carcass maximum width position. Therefore, the outer rim protector can protrude outward in the tire axial direction beyond the rim flange with a smaller rubber volume. That is, the protective effect can be exhibited while further reducing the weight. Note that the contact between the rim flange and the curb mainly occurs on the tire side outside the vehicle. Therefore, the protection effect is achieved by the outer rim protector having the above configuration.

  On the other hand, in the area from the top of the rim protector to the mold splitting position, conventionally, various indications determined by the laws and regulations of the country of sale are engraved. Examples of the display include “size display”, “brand name display”, “DOT stencil display”, “production week display”, “TUBELESS / TUBETYPE display”, “radial display”, “snow tire display”, “REINFORCED / “EXTRA LOAD display”, “Material display”, “Maximum allowable internal pressure, maximum load capacity display”, “Country certification mark display”, “E number display”, “UTQG display”, “Inmetro mark”, etc. In addition, a serration pattern composed of fine ridge ridges is formed in the region in order to make the bulge and dent inconspicuous and improve the appearance quality.

  Here, the said area | region becomes narrow in the vehicle outer side because the said radial direction height H1 becomes large. As a result, there is a risk that a space capable of sufficiently forming the display and the serration pattern cannot be secured.

  However, in the present invention, the radial height H2 of the top portion of the inner rim protector is small, and the region is widened inside the vehicle, so that the above problem is solved. Among the displays defined by laws and regulations, the display of only one of the sidewall portions, that is, the display permitted by the one-side display is included. Therefore, by forming the one-side display in the region on the wide vehicle inner side, it is possible to maintain the appearance quality by providing the serration pattern while forming the necessary display for the entire tire.

It is sectional drawing which shows one Example of the pneumatic tire of this invention. (A), (B) is sectional drawing which expands and shows an inner and outer rim protector.

Hereinafter, embodiments of the present invention will be described in detail.
FIG. 1 shows a meridional section of a tire in a normal internal pressure state that is assembled to a normal rim J and filled with a normal internal pressure. As shown in FIG. 1, the pneumatic tire 1 of the present embodiment is a super flat tire having a flatness ratio of 55% or less, and the bead portion 4 extends from the tread portion 2 to the sidewall portions 3 on both sides in the tire axial direction. A carcass 6 having a carcass main body 6 a that reaches the bead core 5. Each sidewall portion 3 is provided with an annular rim protector 10 extending continuously in the tire circumferential direction.

  The carcass 6 is formed of one or more carcass plies 6A in this example, in which carcass cords are arranged at an angle of, for example, 70 to 90 ° with respect to the tire equator Co. The carcass 6 includes the toroidal carcass main body portion 6a straddling between the bead cores 5 and 5, and a turn-back portion 6b connected to both ends and turned around the bead core 5 from the inner side to the outer side in the tire axial direction. A bead apex rubber 8 having a triangular cross section extending radially outward from the bead core 5 is disposed between the carcass main body portion 6a and the folded portion 6b. The bead apex rubber 8 is made of a hard rubber having a durometer A hardness of, for example, 60 or more, and is reinforced from the bead portion 4 to the sidewall portion 3.

  In the present example, a belt layer 7 and a band layer 9 are sequentially arranged outside the carcass 6 in the radial direction and in the tread portion 2.

  The belt layer 7 is formed of two or more belt plies 7A and 7B in this example, in which belt cords are arranged at about 10 to 35 °, for example, with respect to the tire equator Co. In the belt layer 7, the belt cords cross each other between the plies, thereby increasing the belt rigidity and reinforcing the substantially entire width of the tread portion 2 with a tagging effect.

  The band layer 9 is formed of at least one band ply 9A in which a band cord is spirally wound in the tire circumferential direction. As the band ply 9A, a pair of left and right edge band plies that covers only the outer end portion in the tire axial direction of the belt layer 7 and a full band ply that covers substantially the entire width of the belt layer 7 can be appropriately employed. In this example, the case where the band layer 9 is composed of one full band ply (band ply 9A) is shown. As the carcass cord, belt cord, and band cord, well-known tire cords such as steel cords and organic fiber cords are appropriately employed as in the conventional case.

  Next, rim protectors 10 are disposed on the sidewall portions 3 on both sides.

  Each rim protector 10 has a top portion PA that protrudes most outward in the tire axial direction, and extends continuously in the tire circumferential direction. The top portion PA is located on the inner side in the tire radial direction from the carcass maximum width position 6K and protrudes on the outer side in the tire axial direction from the rim flange Jf. The “carcass maximum width position 6K” is defined as a position where the carcass body 6a protrudes most outward in the tire axial direction in the normal internal pressure state.

  The tire contour line in the tire meridian section is formed by a series of convex arcs at least in the region Y from the top PA to the mold split position PB. In this example, a wide range from the top PA to the tread end Te through the mold split position PB is formed by a series of convex arcs.

  The “series of convex arcs” means curves of convex arcs that are smoothly connected without having an inflection point and a bending point. As this series of convex arcs, for example, a single arc, one in which the radius of curvature continuously changes, and one in which a plurality of arcs with different curvature radii are smoothly connected can be mentioned, and a straight part is included in part It can also be made.

  The “mold split position PB” is defined as a boundary position between a tread mold for forming the tread portion 2 and a side mold for forming the sidewall portion 3. In the tire, the mold split position PB can be visually recognized as a butt mark between the tread mold that moves in the tire radial direction and the side mold that moves in the tire axial direction. The area Y is used as a display space for forming various displays and serration patterns defined by laws and regulations.

  Further, the tire contour line is continuous with the outer side surface 4S of the bead portion 4 through a concave curve M extending in a concave arc from the top portion PA toward the inner side in the tire radial direction inside the top portion PA in the tire radial direction. In the normal internal pressure state, the distance in the tire axial direction between the outer surfaces 4S and 4S matches the rim width.

  In this way, at least in the region Y, the tire contour is formed by a series of convex arcs. Therefore, in this region Y, the radius of curvature of the tire contour is significantly larger than the radius of curvature of the carcass 6. . Therefore, in the buttress portion BT in the vicinity of the mold split position PB, the rubber thickness is secured from the carcass maximum width position 6K to the bead portion 4 while reducing the rubber thickness by bringing the tire contour line close to the carcass 6. It is possible to maintain rigidity. That is, it is possible to maintain the cornering performance (steering stability) while reducing the weight. In particular, the buttress portion BT is a portion where the tire is greatly deformed during running and has a great influence on the rolling resistance. Therefore, rolling resistance performance can be effectively reduced by reducing the weight of the buttress portion BT. In addition, by forming the region Y with a series of convex arcs, the rubber thickness increases in the vicinity of the carcass maximum width position 6K, thereby contributing to the improvement of pinch cut resistance.

  In addition, when the contour line extends in a concave arc from the top PA in the radial direction of the tire as in the conventional rim protector, the rubber thickness only increases locally, and in the vicinity of the carcass maximum width position 6K. The increase in rubber thickness cannot be expected sufficiently. For this reason, the rigidity becomes insufficient, and the effect of improving cornering performance and pinch cut resistance is inferior.

  In the pneumatic tire 1, the formation positions of the rim protectors 10 on both sides are asymmetric. Specifically, as shown in FIGS. 2 (A) and 2 (B), the height H1 in the radial direction from the bead base line BL of the top PAo of the outer rim protector 10o that is outside the vehicle when the vehicle is mounted is set to the vehicle mounting. Sometimes it is larger than the height H2 in the radial direction from the bead base line BL of the top PAi of the rim protector 10i inside the vehicle.

  Thus, by making the radial height H1 large, the top portion PAo of the outer rim protector 10o becomes closer to the carcass maximum width position 6K. Therefore, the outer rim protector 10o can protrude outward in the tire axial direction beyond the rim flange Jf with a smaller rubber volume. That is, the protective effect can be exhibited while further reducing the weight. The contact between the rim flange Jf and the curbstone or the like mainly occurs on the tire side outside the vehicle. Therefore, the protection effect is achieved by the outer rim protector 10o having the above configuration.

  Further, since the height H1 in the radial direction is increased, the region Y is narrowed outside the vehicle. As a result, there is a risk that a space capable of sufficiently forming the display and the serration pattern cannot be secured.

  However, in the present invention, the above-mentioned problem is solved by reducing the height H2 in the radial direction and widening the region Y inside the vehicle. That is, by forming one of the above-mentioned displays that is permitted to be displayed on one side in a wide area Y inside the vehicle, the entire tire is provided with a serration pattern to maintain the appearance quality while forming the necessary display. It becomes possible.

  In the present invention, the ratio H1 / H0 between the radial height H0 from the bead base line BL at the carcass maximum width position 6K and the radial height H1 at the outer rim protector 10o is 0.65 to 0.83. The range of is preferable. The ratio H2 / H0 between the radial height H0 and the radial height H2 of the inner rim protector 10i is preferably in the range of 0.52 to 0.63.

  When the ratio H1 / H0 is less than 0.65, the top PAo of the outer rim protector 10o is greatly separated from the carcass maximum width position 6K. Therefore, the rubber volume of the outer rim protector 10o for obtaining the protection effect is increased, which is disadvantageous for weight reduction. On the other hand, if the ratio H1 / H0 exceeds 0.83, the region Y becomes too narrow, and it becomes difficult to sufficiently form a display and a serration pattern. Alternatively, the degree of freedom of display and serration pattern arrangement, that is, the degree of freedom in design design is reduced.

  On the other hand, when the ratio H2 / H0 is less than 0.52, the top portion PAi is largely separated from the carcass maximum width position 6K, so that the rubber volume of the rim protector 10i in order to obtain a protection effect is increased. Or, the protection effect is reduced. On the other hand, if the ratio H2 / H0 exceeds 0.63, the area Y inside the vehicle becomes narrow, and there is a tendency that a space for receiving a display or serration pattern that is difficult to arrange in the area Y outside the vehicle cannot be secured. . Therefore, in order to make a necessary display for the entire tire while reducing the weight, (H1-H2) / H0 is preferably 0.1 or more, more preferably 0.15 or more.

  In the outer rim protector 10o, the ratio T1 / L1 between the tire axial distance L1 from the outer surface 4S of the bead portion 4 to the top portion PAo and the thickness T1 from the top portion PAo to the carcass 6 is 0.70. A range of ˜0.75 is preferred. In the inner rim protector 10i, the ratio T2 / L2 between the tire axial distance L2 from the outer surface 4S of the bead portion 4 to the top portion PAi and the thickness T2 from the top portion PAi to the carcass 6 is 0.67. A range of ˜0.77 is preferred. The folded portion 6b of the carcass 6 extends beyond the apex PA outward in the tire radial direction, and terminates in the vicinity of the carcass maximum width position 6K in this example. Therefore, the thicknesses T1 and T2 are shown as thicknesses from the respective top portions PAi and PAo to the turn-up portion 6b of the carcass 6, respectively.

  When the ratio T1 / L1 is less than 0.70, the thickness T1 tends to be small and / or the distance L1 tends to be large. When the distance L1 is large, the protection effect is excellent, but it is disadvantageous for weight reduction. Moreover, when thickness T1 becomes small, the improvement effect of a protection effect, cornering property, and pinch cut-proof property will fall. Conversely, when the ratio T1 / L1 exceeds 0.75, the thickness T1 tends to be large and / or the distance L1 tends to be small. When the thickness T1 is increased, the protection effect, cornering property, and pinch cut resistance are improved, but it is disadvantageous for weight reduction. When the distance L1 is small, it is advantageous for weight reduction, but the protection effect tends to be reduced.

  When the ratio T2 / L2 is less than 0.67, the thickness T2 tends to be small and / or the distance L2 tends to be large. When the distance L2 is large, the protection effect is excellent, but it is disadvantageous for weight reduction. Moreover, when thickness T2 becomes small, the improvement effect of a protection effect, cornering property, and pinch cut-proof property will fall. Conversely, when the ratio T2 / L2 exceeds 0.77, the thickness T2 tends to be large and / or the distance L2 tends to be small. When the thickness T2 is increased, the protective effect, the cornering property, and the pinch cut resistance are improved, but it is disadvantageous for weight reduction. Further, when the distance L2 is small, it is advantageous for weight reduction, but the protection effect tends to be reduced.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  In order to confirm the effect of the present invention, a pneumatic tire (225 / 45R17) having a flatness ratio of 45% and having the structure shown in FIG. 1 was prototyped based on the specifications shown in Table 1, and the tire mass was measured for each sample tire. Appearance quality, design freedom, protection performance, anti-pinch cut performance, and steering stability performance were tested and compared with each other. Each tire has substantially the same specifications except those listed in Table 1. In Comparative Example 1, the inner and outer rim protectors are formed at the same position, and the region Y is formed by a series of convex arcs.

(1) Tire mass:
The mass of one tire was measured and evaluated by an index with Comparative Example 1 as 100. The smaller the value, the smaller the tire mass and the lighter.

(2) Appearance quality:
The tire was visually inspected outdoors under the conditions of a rim (17 × 7.5 JJ) and an internal pressure (230 kPa). Then, whether or not the bulge dent in the sidewall portion is not noticeable due to serration was evaluated on a five-point scale based on Comparative Example 1. The larger the value, the wider the space for forming the serration, and the better the appearance quality (appearance in appearance).

(3) Design freedom:
The degree of freedom in actually manufacturing the mold was evaluated on a five-point scale based on Comparative Example 1. The higher the value, the higher the degree of freedom.

(4) Protection performance:
Tires are mounted on all wheels of a vehicle (2500cc domestic FF passenger car) under the conditions of a rim (17 x 7.5 JJ) and internal pressure (230 kPa), and the rim when riding on the curb at 60 km / h The degree of damage was evaluated on a five-point scale with reference to Comparative Example 1. The larger the value, the better the protection performance.

(5) Anti-pinch cut performance:
In accordance with JIS D4230 Section 6.1 “Tire Strength (Fracture Energy) Test”, a plunger tester was used to support the rim (17 × 7.5JJ) and the internal pressure (230 kPa) sideways. The fracture energy at the maximum carcass width position of the test tire was measured. The results were evaluated on a 5-level scale based on Comparative Example 1. It can be said that the larger the value, the better the anti-pinch cut performance.

(6) Steering stability performance:
The tires were mounted on all wheels of a vehicle (2500cc domestic FF passenger car) under the conditions of a rim (17 × 7.5JJ) and internal pressure (230 kPa). Then, the cornering performance when running on a dry asphalt test course was evaluated on a five-point scale based on Comparative Example 1 based on the driver's sense. The larger the value, the better the steering stability.

  As shown in the table, it can be confirmed that the tires of the examples can reduce the weight of the tire while exhibiting a high protection effect.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 4S Outer side surface of bead part 5 Bead core 6 Carcass 6a Carcass main body part 6K Carcass maximum width position 10, 10i, 10o Rim protector PA, PAi, PAo Top part PB Mold split position Y area

Claims (3)

A pneumatic tire having a carcass having a carcass main body extending from a tread portion through sidewall portions on both sides in the tire axial direction to a bead core of the bead portion, and having a flatness ratio of 55% or less,
Each sidewall has a rim protector that continuously extends in the tire circumferential direction with the top most protruding outward in the tire axial direction,
The tire contour line in the tire meridional section is formed by a series of convex arcs in a region from the top to a mold split position which is a boundary between a tread mold for forming the tread portion and a side mold for forming the sidewall portion. With
The outer rim protector outside the vehicle when mounted on the vehicle has a radial height H1 from the bead base line at the top of the rim protector, and the radial height from the bead base line at the top of the rim protector inside the vehicle when mounted on the vehicle. A pneumatic tire characterized by being larger than the height H2.   The ratio H1 / H0 between the radial height H0 from the bead base line at the carcass maximum width position where the carcass main body protrudes most outward in the tire axial direction and the radial height H1 at the outer rim protector is 0. The ratio H2 / H0 of the range 65-0.83 and the radial height H0 and the radial height H2 of the inner rim protector is in the range of 0.52-0.63. The pneumatic tire according to claim 1. In the outer rim protector, a ratio T1 / L1 between a tire axial distance L1 from the outer surface of the bead portion to the top and a thickness T1 from the top to the carcass is in a range of 0.70 to 0.75,
In the inner rim protector, a ratio T2 / L2 between a tire axial distance L2 from the outer surface of the bead portion to the top portion and a thickness T2 from the top portion to the carcass is in a range of 0.67 to 0.77. The pneumatic tire according to claim 1, wherein the pneumatic tire is provided.

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