JP5331558B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire with improved anti-hydroplaning performance when traveling straight and turning on a wet road surface.

In a conventional pneumatic tire, a tread portion is provided with a circumferential groove extending in the tire circumferential direction and a lateral groove extending in the tire width direction. The circumferential groove drains the tire in the front-rear direction, and the lateral groove drains the tire laterally. Especially when driving on wet roads, drain the water on the roads through these grooves to increase the contact between the tread and the road surface, thereby increasing the inter-surface frictional force and thus the road grip force. In addition, the occurrence of hydroplaning was suppressed, and excellent driving stability was achieved to improve driving safety.
In general, as shown in FIG. 2, such a groove improves drainage as the groove area on the tread surface increases, and for example, as schematically shown in FIG. By providing it along the flow of water, drainage can be improved.

  By the way, as schematically shown in FIG. 4, the hydroplaning phenomenon is caused by the fact that the water pressure generated by the collision between the tire and the water on the road surface becomes larger than the road surface contact pressure of the tread surface. It is known that the contact area of the tread surface is reduced due to water intruding into the water and causing the water to lift the tire from the road surface.

In contrast to the occurrence of such a decrease in hydroplaning, conventionally, the groove area was increased to improve drainage, thereby suppressing the occurrence. There is a possibility that the steering stability may be lowered due to a decrease in the rigidity of the part.
Also, when running with tires attached to the vehicle, the ground contact shape of the tire changes between straight running and turning, and during turning, the ground pressure increases on the outside of the vehicle and on the inside of the vehicle. Since the contact pressure is low, the inside of the mounting tends to float easily.

  For this reason, in Patent Document 1, the negative ratio A (= B / C), which is the ratio of the negative ratio B of the outer region when the tread is mounted to the negative ratio C of the inner region when the tread is mounted, with the tire equatorial plane as a boundary. A technique has been proposed in which the groove area on the inner side of the mounting is made larger than that on the outer side of the mounting so that the turning performance of the wet road surface is improved.

  However, the tire disclosed in Patent Document 1 can improve the turning performance on the wet road surface, but the vehicle is fitted with the tire when traveling straight (FIG. 5 (b)) and when turning (FIG. 5). 5 (c)) is different from that of the tire alone (FIG. 5 (a)) when the vehicle is traveling straight as shown in FIG. 5 (b), for example, Under the application of negative camber, the contact pressure is high on the inner side and the contact pressure is lower on the outer side, but if a slip angle is applied to the tire for turning, the lateral force required for turning will be generated. Accordingly, since the outside of the mounting is grounded at a high ground pressure, further improvement that can achieve both the displacement of the high ground pressure region during straight traveling and cornering has been desired.

JP-A-7-164826

  Accordingly, the object of the present invention is to provide a high level of compatibility between the anti-hydroplaning performance when turning on a wet road surface and the anti-hydroplaning performance when driving straight on a wet road surface. To provide tires.

In the pneumatic tire according to the present invention, a plurality of circumferential grooves extending in the tread circumferential direction and a plurality of lateral grooves extending in the tread width direction are arranged on the tread surface, and an asymmetric pattern is formed around the tire equatorial plane. The total groove area of the circumferential groove that will be located inside the vehicle from the tire equator plane in the mounting posture on the vehicle is the entire circumferential groove that will be located outside the vehicle. The groove area is larger than the groove area, the entire groove area of the lateral groove outside the tire equator is larger than the entire groove area of the lateral groove inside the tire, and the total groove area of the outer groove is equal to the total groove area of the inner groove. respect, Ri Na provided in a range of 70% to 90%, in mounting attitude of the vehicle, the groove area of each circumferential groove in the inner side than the tire equatorial plane, of the mounting outside the groove area of any circumferential groove Increase the groove area of each lateral groove on the outside of the mounting, Those formed by larger than the groove area of the lateral grooves of the shift.

Here, the groove area is determined from the length, width and number of grooves.
The lateral grooves include those inclined in the range of 0 to 80 ° in the tread circumferential direction.
The length and width of the groove are industrial standards effective in the region where tires are produced and used. In Japan, JATMA (Japan Automobile Tire Association) YEAR BOOK, in Europe, ETRTO (European Tire and Rim Technical Organization) ) STANDARDDS MANUAL, in the United States TRA (THE TIRE and RIM ASSOCATION INC.) YEAR BOOK, etc., the tire is assembled, and the tire is in a state filled with the highest air pressure as defined by the standards such as JATMA The distance measured on the tread is measured below.

Preferably, the extending length of the lateral groove on the outer side of the mounting is made larger than the extending length of the lateral groove on the inner side of the mounting in the tire width direction.
Here, the “extending length of the lateral groove in the tire width direction” means a length measured by the center line of the groove, and in the case of an inclined groove, it means the length in the width direction.

  By the way, the total groove area of the circumferential groove on the inner side of the mounting is in the range of 100 to 200% with respect to the total groove area of the outer peripheral groove of the mounting, and the total groove area of the lateral groove on the outer side of the mounting is the total groove of the lateral groove on the inner side of the mounting. It is preferable to set it as the range of 100-300% with respect to an area.

  In the pneumatic tire of the present invention, the entire groove area of the circumferential groove that is positioned on the inner side of the vehicle from the tire equator plane in the mounting posture on the vehicle is the entire groove of the circumferential groove that is positioned on the outer side of the vehicle. By making it larger than the area, especially under negative camber conditions, the land area on the inner side of the installation tends to contact the road surface, and the land area on the inner side tends to rise from the road surface. Drainability can be improved by increasing the groove area of the circumferential groove on the inner side of the mounting, which is a longer region. As a result, it is possible to improve the hydroplaning performance during straight running.

  In addition, by increasing the total groove area of the lateral groove on the outer side of the tire from the tire equator surface than the total groove area of the lateral groove on the inner side of the tire, the groove area on the outer side of the mounting where the ground pressure increases during turning can be increased. The drainage efficiency can be increased. As a result, it is possible to improve the anti-hydroplaning performance during turning.

  In addition, by providing the total groove area of the outer groove of the mounting in the range of 70 to 90% with respect to the total groove area of the inner groove, both the rigidity of the tread portion and the drainage can be achieved. be able to.

  That is, if it is less than 70%, the groove area on the outer side of the mounting is reduced and drainage efficiency is reduced, so that hydroplaning occurs on the outer side of the mounting during straight traveling and turning, and if it exceeds 90%, the groove area on the inner side of the mounting is increased. It becomes small and drainage efficiency deteriorates, and there is a possibility that hydroplaning occurs inside the mounting.

It is a partial development view of a tread pattern showing one embodiment of a pneumatic tire of the present invention. It is a figure showing typically drainage on a tread surface. It is a figure showing typically drainage on a tread surface. It is a figure which shows a hydroplaning phenomenon typically. (A) is a tread grounding shape of a single tire, (b) is a tread grounding shape when traveling straight with a tire attached to a car, and (c) is a tire tread grounding when the tire is mounted on a car. It is a figure which shows each tread grounding shape. (A)-(e) is the partial expanded view of the tread pattern which shows embodiment of the conventional pneumatic tire.

Hereinafter, the pneumatic tire of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a partial development view of a tread pattern showing one embodiment of the pneumatic tire of the present invention.
Since the reinforcing structure inside the tire is the same as that of a general radial tire or bias tire, illustration is omitted.

The tread pattern shown in FIG. 1 is an asymmetric pattern, and the tire shown in FIG. 1 is used in a posture in which the left side is a vehicle-mounted inner side.
In the figure, reference numeral 1 denotes the entire tread surface. The tread surface 1 has a plurality of circumferential grooves extending in the tread circumferential direction, two center circumferential grooves 2in and 2out provided in the figure with a tire equator line therebetween. The shoulder circumferential grooves 3in and 3out adjacent to the respective side portions of the center circumferential grooves 2in and 2out are disposed.
Between the two circumferential grooves adjacent to each other, in the figure, between the two center circumferential grooves 2in and 2out, the central land portion 4 is interposed, and between the center circumferential grooves 2in and 2out and the shoulder circumferential grooves 3in and 3out, the intermediate land The sections 5in and 5out are partitioned, and the shoulder land sections 6in and 6out are partitioned between the shoulder circumferential grooves 3in and 3out and the tread side edge.

In the shoulder land portions 6in and 6out, a plurality of shoulder blocks are formed by the lateral grooves 7in and 7out that extend across the shoulder land portions 6in and 6out in the tread width direction from the shoulder circumferential grooves 3in and 3out, respectively, and open to the tread side edge. 8in and 8out are partitioned.
By providing the lateral grooves 7in and 7out on the outermost side in the tire width direction, the drainage distance from the circumferential grooves 3in and 3out to the outside of the road surface is shortened, and drainage efficiency can be increased.

In this pneumatic tire, the total groove area of the circumferential groove that is located inside the vehicle from the tire equator plane is made larger than the total groove area of the circumferential groove that is located outside the vehicle, and the tire equator The total groove area of the lateral groove 7out outside the mounting surface is made larger than the total groove area of the lateral groove 7in inside the mounting, and the total groove area of the mounting outside groove is set to 70 to Provide in the range of 90%.
Preferably, the outer side of the mounting is a lateral groove and the inner side of the mounting is a groove arrangement based on a circumferential groove.

  Here, for example, the center circumferential groove 2in has a groove width of 2 to 15 mm and a groove depth of 3 to 15 mm, and the center circumferential groove 2out has a groove width of 2 to 15 mm and a groove depth of 3 to 15 mm. The shoulder circumferential groove 3in has a groove width of 2 to 15 mm and a groove depth of 3 to 15 mm, and the shoulder circumferential groove 3out has a groove width of 2 to 15 mm and a groove depth of 3 to 15 mm. The lateral groove 7in has a groove width of 2 to 20 mm, a groove depth of 3 to 15 mm, and a maximum length in the tire width direction of 20 to 40 mm. The lateral groove 7out has a groove width of 2 to 20 mm and a groove depth. The maximum length in the tire width direction can be set to 3 to 15 mm and 20 to 40 mm.

  In this pneumatic tire, preferably, in the mounting posture to the vehicle, the groove area of each circumferential groove on the inner side of the tire from the tire equator surface is larger than the groove area of any of the peripheral grooves on the outer side of the tire, and each lateral groove on the outer side of the tire is mounted. The groove area is made larger than the groove area of any of the lateral grooves inside the mounting.

Preferably, the maximum groove width of the inner circumferential groove is made wider than the maximum groove width of the outer circumferential groove.
With this configuration, it is possible to improve drainage performance during straight traveling and turning, and to improve the hydrobrain resistance.

  And preferably, the groove width of the circumferential groove can be narrowed from the mounting inner side to the mounting outer side, and this configuration improves the steering stability when shifting from straight traveling to turning traveling. In addition to improving the stability of the land by improving the rigidity of the land area in the outer area that is mainly grounded during cornering, the groove width is increased in the inner area that is mainly installed during straight running. Can be increased.

  By the way, the extension length in the tire width direction of the lateral groove 7out on the outer side of installation is larger than the extension length in the tire width direction of the lateral groove 7in on the inner side of installation. Improve drainage on the outside to ensure road surface contact pressure.

  Also preferably, the total groove area of the peripheral groove on the inner side of the mounting is in a range of 100 to 200% with respect to the total groove area of the peripheral groove on the outer side of the mounting, and the total groove area of the lateral groove on the outer side of the mounting is The range is 100 to 300% with respect to the total groove area of the lateral grooves.

  By setting the groove areas of the circumferential groove and the lateral groove as the ratio, it is possible to achieve both drainage and land rigidity, and to ensure hydroplaning resistance and steering stability.

  Next, tire tires of size 195 / 65R15 and comparative tires 1 to 4 were made as prototypes, and as shown in Table 1, the hydroplaning performance was evaluated by changing each specification.

(Straight running hydroplaning performance)
For each of the example tires and comparative tires 1 to 5, a rim size of 6J × 15 and a tire pressure of 210 kPa was applied with a negative camber of 0.5 °, and the tire was accelerated in a straight line through a pool with a water depth of 10 mm. The index evaluation was performed by comparing the speed at which the wheel runs idle, and the results are shown in Table 2. The evaluation in Table 2 indicates that the larger the numerical value, the better.

(Turning hydroplaning performance)
For each of the example tires and comparative tires 1 to 5, a rim size of 6 J × 15 and a tire pressure of 210 kPa was attached with a negative camber of 0.5 ° and installed in a pool with a water depth of 6 mm at a corner with a radius of 100 m. The vehicle was entered at a speed of 65, 70, 75, 80, 85 km / h, the lateral acceleration applied to the vehicle in the pool was measured, and obtained in tests of turning speeds of 65, 70, 75, 80, 85 km / h. The total lateral acceleration is evaluated as an index, and the results are shown in Table 2. The evaluation in Table 2 indicates that the larger the numerical value, the better.

From the results of Table 2, the example tires showed improved hydroplaning performance for both the straight running and the turning running compared to the comparative tires 1-5.
In addition, by increasing the groove area of the lateral groove on the outer side of mounting from the comparative tires 1 and 2, it was possible to improve the anti-hydroplaning performance during turning. Further, in Comparative Example 3, it is considered that by increasing the groove area of the peripheral groove on the inner side of the mounting, the groove area on the outer side of the mounting is too small so that drainage cannot catch up and hydroplaning occurs from the outer side of the mounting. The hydroplaning performance during straight running was equivalent to that of Comparative Example 1.

1 tread tread 2in, 2out center circumferential groove 3in, 3out shoulder circumferential groove 4 central land part 5in, 5out intermediate land part 6in, 6out shoulder land part 7in, 7out lateral groove 8in, 8out shoulder block

Claims (3)

In the pneumatic tire formed by arranging a plurality of circumferential grooves extending in the tread circumferential direction and a plurality of lateral grooves extending in the tread width direction on the tread surface, and forming an asymmetric pattern around the tire equator plane,
In the mounting posture on the vehicle, the total groove area of the circumferential groove that will be located inside the vehicle from the tire equator plane is larger than the total groove area of the circumferential groove that will be located outside the vehicle,
The total groove area of the lateral groove outside the tire equator is larger than the total groove area of the lateral groove inside the tire,
The total groove area of the mounting outside of the groove, the total groove area of the groove of the inner side, Ri Na provided in a range of 70% to 90%,
In the mounting position on the vehicle, the groove area of each circumferential groove on the inner side of the tire from the equator plane is larger than the groove area of any circumferential groove on the outer side of the tire, and the groove area of each lateral groove on the outer side of the tire is pneumatic tire according to claim Rukoto such made larger than the groove area of any lateral grooves. 2. The pneumatic tire according to claim 1 , wherein an extending length in a tire width direction of the lateral groove on the outer side of the mounting is larger than an extending length in the tire width direction of the lateral groove on the inner side of the mounting. The total groove area of the inner circumferential groove is 100 to 200% of the total groove area of the outer circumferential groove, and the total groove area of the outer lateral groove is the total groove area of the inner lateral groove. The pneumatic tire according to claim 1 or 2 , wherein the content is in a range of 100 to 300%.

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