Pneumatic radial tire

Abstract

The invention provides a pneumatic radial tire which is characterized in that a tire crown part of a tire body profile comprises one or more sections of tangent arcs, at least three longitudinally arranged main grooves and a plurality of transverse grooves are formed in the surface of the tire crown part, and an included angle alpha between a connecting line of a central point O and an end point P1 of the arc of the tire crown part and a horizontal line is less than or equal to 7 degrees; the included angle beta between the connecting line of the contour center position point M of the outermost main groove and the center point O of the crown arc and the horizontal line is less than or equal to 1/2 alpha; and a plurality of pits with unlimited shapes and unlimited arrangement modes are formed in the bottom surfaces of the main ditches or the transverse ditches. By optimizing the contour of the tire crown part and the design of the arc contour of the bottom of the main groove, the tire which is more uniform in tire crown arc growth and better in groove crack resistance under the inflation standard air pressure condition is obtained, and the tire has better wet land drainage performance by additionally arranging the pits in the bottom of the groove.

Description

technical field [0001] The invention relates to the technical field of tire design and manufacture, in particular to a pneumatic radial tire. Background technique [0002] In the prior art, pneumatic tires usually have a stiffness difference between the middle area of ​​the crown and the shoulder area, and this difference is likely to cause uneven inflation of the crown of the tire (subsequently referred to as uneven growth of the crown arc). Uniform crown arc growth may create a live point in the center of the tire shoulder, which may cause high stress on the bottom of the shoulder circumferential groove, easily causing the circumferential groove in the shoulder area of ​​the tire to bottom out cracking problem. Attempts in the industry to achieve uniform tire inflation have mostly focused on increasing the structural stiffness of the belt ply assembly in the crown portion, or by controlling the tension gradient of the cap ply between the shoulders and the middle of the cr...

AI Technical Summary

Problems solved by technology

[0002] In the prior art, pneumatic tires usually have a stiffness difference between the middle area of ​​the crown and the shoulder area, and this difference is likely to cause uneven inflation of the crown of the tire (subsequently referred to as uneven growth of the crown arc). Uniform crown arc growth may create a live point in the center of the tire shoulder, which may cause high stress on the bottom of the shoulder circumferential groove, easily causing the circumferential groove in the shoulder area of ​​the tire to bottom out cracking problem

Attempts in the industry to achieve uniform tire inflation have mostly focused on increasing the structural stiffness of the belt ply assembly in the crown portion, or by controlling the tension gradient of the cap ply between the shoulders and the middle of the crown; but Increase the uniform inflation of the tire by increasing the structural stiffness of the belt layer, which will increase the cost and weight of the tire, and may have an adverse effect on the rolling resistance of the tire; while the method of controlling the tension gradient of the cap layer, the tire manufacturing process requirements High, difficult to achieve

[0003] At the same time, in order to improve the wet drainage performance of tires, the commonly used technical means in the industry is to increase the design width of tire tread grooves (including longitudinal grooves and transverse grooves), or to form 3D chamfers by cutting the groove edges to improve tire tire tread. However, it will reduce the overall pattern stiffness of the tire, which will directly affect the handling performance and braking performance of the tire, and the increase of the groove width will aggravate the difference in the rigidity of the pattern blocks on both sides of the tire groove, resulting in the tire running in the middle of the groove. The deformation difference on both sides of the groove increases, and the problem of groove cracking is more likely to occur; and the design of forming a 3D chamfer by cutting the edge of the groove can take into account the improvement of the cavity water capacity of the tire tread groove and the rigidity of the tread block , but it only slightly improves the wet performance of the new tires, and the improvement effect is not good

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