CN113352818A - Pneumatic tire for cross country racing - Google Patents

Abstract

The invention provides a pneumatic tire for cross-country racing, which comprises a tire body, wherein the tire body comprises a tread part, a shoulder part, a sidewall part, a bead part and a tire body part, the tread part is provided with a central region pattern and a shoulder pattern, the shoulder pattern is formed by arranging shoulder double patterns consisting of a main shoulder pattern and a secondary shoulder pattern at intervals along the circumferential direction of the tire, the main shoulder pattern and the secondary shoulder pattern both extend from the tread part to the sidewall part, the shoulder double patterns are formed by a tread grounding section, a shoulder linkage section and a sidewall support section, the shoulder linkage section connects the tread grounding section and the sidewall support section, and the profiles of the shoulder linkage section and the sidewall support section of the main shoulder pattern and the secondary shoulder pattern forming the shoulder double patterns are not overlapped when being observed from the section direction of the tire. The pneumatic tire for the cross country race provided by the invention can improve the traction performance and the durability under low wind pressure running while taking the cross country performance into consideration.

Description

Pneumatic tire for cross country racing

Technical Field

The invention relates to the field of pneumatic tires, in particular to a pneumatic tire for a cross country race.

Background

The existing racing car needs to have good traction performance and driving performance, and in order to meet the performance requirements, the existing pneumatic tire for racing car matched with the existing racing car is usually provided with blocky patterns on the tread of the tire so as to increase the gripping capacity of the tire and a contact surface; axial and circumferential pattern grooves are formed among the blocky patterns so as to fully drain water and mud; the side wall of the tire is provided with the blocky side wall patterns, so that the side wall of the tire is prevented from being punctured or scratched by a sharp object in the driving process. However, since the road conditions for the go-anywhere racing vehicle are complex and the requirements for climbing and obstacle-surmounting capabilities are high, the pneumatic tires for the go-anywhere racing vehicle usually need to run under low wind pressure or even zero wind pressure. The existing pneumatic tire for cross country racing is easy to have the phenomenon of tire knockover caused by insufficient support property of a tire body under low wind pressure, and further the durability of the tire is influenced.

Patent publication No. CN109352344A discloses a pneumatic tire in which a plurality of protrusions protruding outward in the tire axial direction are juxtaposed on the outer surface of a sidewall portion in the tire circumferential direction, aiming to improve the durability of the tire sidewall portion and the driving force at running on a muddy ground or the like by providing the protrusions and a plurality of recesses on the protrusions, but the protrusions provided on the tire sidewall cannot achieve effective support of the tire for long-term running when the tire is under low wind pressure or even zero wind pressure.

The patent with publication number CN212499749U discloses a pneumatic tire, the tread and the sidewalls of which are integrally formed, the tread is provided with two sets of first block groups, the first block groups include a plurality of first blocks, and the plurality of first blocks are integrally formed with the tread, aiming at making the pneumatic tire have good effect of mud advancing stability. This pneumatic tire still is provided with the second decorative pattern piece in the one side that first decorative pattern piece group is close to the side wall, and first decorative pattern groove and second decorative pattern groove have been seted up to one side that the second decorative pattern piece is towards the side wall, but this design can weaken the decorative pattern rigidity, leads to the lateral wall support nature and the durability of tire under low wind pressure to receive the influence.

The publication US008434534B2 discloses a pneumatic tire with sidewall protection blocks, suitable for off-the-road tires, whose sidewalls have blocks to increase sidewall thickness, protecting the sidewalls from puncturing by debris; the side wall pattern blocks are provided with inclined surfaces to protect the side walls from being grabbed or torn by sharp objects; the sidewall blocks have surfaces that grab the rut edges and are arranged in a coaxial and overlapping manner on the tire sidewall to provide good traction performance and reasonable sidewall weight distribution when the tire is at zero wind pressure. However, the linkage between the side wall pattern block and the tread pattern is not enough, and the side wall support and the durable running performance of the tire running under low wind pressure still have a great improvement space.

Therefore, it is an object of the present invention to develop and improve a pneumatic tire for off-road racing that satisfies the off-road performance and can improve the traction performance and durability under low wind pressure running.

Disclosure of Invention

In view of the above problems, the present invention provides a pneumatic tire for a cross country race, in which a central region pattern and a shoulder pattern are provided in a tread portion, and the structure of the shoulder pattern is optimally designed, thereby improving traction performance and durability under low wind pressure running while taking into account cross country performance of the pneumatic tire for a cross country race.

The technical scheme of the invention is as follows:

a pneumatic tire for cross-country racing comprises a tire body, wherein the tire body comprises a tread part, a shoulder part, a sidewall part, a bead part and a carcass part, and the tread part is provided with a central region pattern and a shoulder part pattern;

the shoulder double patterns are formed by arranging shoulder double patterns at intervals along the circumferential direction of the tire, the shoulder double patterns comprise main shoulder patterns and secondary shoulder patterns, the main shoulder patterns and the secondary shoulder patterns are arranged at intervals along the circumferential direction of the tire to form shoulder main grooves, and the main shoulder patterns and the secondary shoulder patterns extend from the tread part to the sidewall part;

the main shoulder pattern includes a main tread ground section, a main shoulder linking section, and a main sidewall support section, the main shoulder linking section being connected to the main tread ground section on one side and to the main sidewall support section on the other side, the main sidewall support section terminating from the shoulder portion to the sidewall portion via a tire section horizontal reference line, the main sidewall support section having a thickness gradually decreasing from a boundary line of the main shoulder linking section and the main sidewall support section to the sidewall portion;

the secondary shoulder pattern comprises a secondary tread grounding section, a secondary shoulder linkage section and a secondary side wall supporting section, one side of the secondary shoulder linkage section is connected with the secondary tread grounding section, the other side of the secondary shoulder linkage section is connected with the secondary side wall supporting section, the secondary side wall supporting section extends from the shoulder part to the sidewall part through a tire section horizontal datum line and is terminated, and the thickness of the secondary side wall supporting section is gradually reduced from the boundary line of the secondary shoulder linkage section and the secondary side wall supporting section to the sidewall part;

the shoulder linking sections and the sidewall support sections constituting the shoulder double patterns do not overlap in profile when viewed from the tire cross-sectional direction.

Further, the boundary between the primary tread ground contact section and the primary shoulder linkage section is disposed axially inward of the vertical edge reference line of the tire section, and the boundary between the secondary tread ground contact section and the secondary shoulder linkage section is disposed axially outward of the vertical edge reference line of the tire section.

Further, the boundary between the primary tread ground contact section and the primary shoulder linkage section is disposed axially outward of the vertical edge reference line of the tire section, and the boundary between the secondary tread ground contact section and the secondary shoulder linkage section is disposed axially inward of the vertical edge reference line of the tire section.

Further, the boundary of the main tread grounding section and the main shoulder linkage section is arranged on the axial outer side of the vertical edge datum line of the tire section, and the boundary of the secondary tread grounding section and the secondary shoulder linkage section is arranged on the axial outer side of the vertical edge datum line of the tire section;

the axial distance from the boundary of the main shoulder linkage section and the main side wall supporting section to the vertical edge reference line of the tire section on the same side is equal to the axial distance from the boundary of the secondary shoulder linkage section and the secondary side wall supporting section to the vertical edge reference line of the tire section on the same side.

Further, the axial distance between the farthest end point of the radial profile of the main shoulder pattern axially away from the central plane of the tire and the farthest end point of the radial profile of the secondary shoulder pattern axially away from the central plane of the tire is 10.0-18.0 mm.

Furthermore, the axial distance from the boundary of the main tread grounding section and the main shoulder linkage section to the vertical edge datum line of the tire section on the same side is 4.0% -12.0% of the width of the tire section, and the axial distance from the boundary of the secondary tread grounding section and the secondary shoulder linkage section to the vertical edge datum line of the tire section on the same side is 10.0% -17.0% of the width of the tire section.

Further, the ratio of the shortest distance from the farthest point axially away from the tire central plane to the radial outer contour of the tire body part on the main shoulder pattern radial contour to the shortest distance from the farthest point axially away from the tire central plane to the radial outer contour of the tire body part on the main side wall supporting section radial contour is (2.5-7.0): 1;

the ratio of the shortest distance from the farthest end point axially away from the tire central plane to the radial outer contour of the tire body part on the radial profile of the secondary shoulder pattern to the shortest distance from the farthest end point axially away from the tire central plane to the radial outer contour of the tire body part on the radial profile of the secondary side wall supporting section is (5.0-8.5): 1.

Further, one side circumference profile of the main side wall supporting section is provided with a main first tip part with a plurality of curved surface profiles, one side circumference profile of the secondary side wall supporting section is provided with a secondary first tip part with a plurality of curved surface profiles, and the bending directions of the main first tip part and the secondary first tip part at the outer side of the circumference of the side wall part are consistent.

Furthermore, a main notch part is arranged at the main tip part, and the notch depth of the main notch part is 15% -60% of the thickness of the side part; the secondary sharp portion is provided with a secondary notch portion, and the notch depth of the secondary notch portion is 15% -60% of the thickness of the tire side portion.

Furthermore, a main second tip part with a plurality of curved surface profiles is arranged on one side, provided with the circumferential profile of the main first tip part, of the main side wall supporting section, and a secondary second tip part with a plurality of curved surface profiles is arranged on one side, provided with the circumferential profile of the secondary first tip part, of the secondary side wall supporting section, and the bending directions of the main second tip part and the secondary second tip part on the circumferential outer side of the side wall part are consistent;

the main two-point part is provided with a main step part, the step depth of the main step part is 15% -60% of the thickness of the side portion where the main step part is located, the secondary two-point part is provided with a secondary step part, and the step depth of the secondary step part is 15% -60% of the thickness of the side portion where the secondary step part is located.

The invention has the beneficial effects that:

(1) the pneumatic tire for the cross country race is provided with a central area pattern and a shoulder pattern on a tread portion, wherein the shoulder pattern is formed by arranging shoulder double patterns consisting of a main shoulder pattern and a secondary shoulder pattern at intervals along the circumferential direction of the tire. Both a main shoulder pattern and a sub shoulder pattern extend from the tread portion to the sidewall portion, the main shoulder pattern including a main tread ground-contacting section, a main shoulder linkage section, and a main sidewall support section, the sub shoulder pattern including a sub tread ground-contacting section, a sub shoulder linkage section, and a sub sidewall support section. The shoulder link segments connect the tread ground engaging segments and the sidewall support segments such that the shoulder link segments are capable of providing a stable support effect for the shoulder pattern. When the tire runs under low wind pressure or even zero wind pressure, the supporting effect of the side wall supporting section on the side wall part is enhanced under the linkage effect of the shoulder part linkage section, and the side wall part is prevented from collapsing under low pressure or loss of pressure to cause rim knocking over, so that the durability of the tire under low pressure or loss of pressure is improved.

(2) The axial distance from the radial outline of the main shoulder linkage section to the central plane of the tire is not more than the axial distance from the radial outline of the secondary shoulder linkage section to the central plane of the tire, the axial distance from the radial outline of the main sidewall support section to the central plane of the tire is not more than the axial distance from the radial outline of the secondary sidewall support section to the central plane of the tire, namely, when the tire is observed from the section direction, the outlines of the shoulder linkage section and the sidewall support section of the main shoulder pattern and the secondary shoulder pattern forming the shoulder double pattern are not overlapped, and a profile surface with staggered arrangement is formed in the section direction of the tire, so that the gripping capacity of the shoulder double pattern under different road conditions such as soft soil, silt, rocks and the like is improved, and the traction performance of the tire is improved.

(3) The main side wall supporting section extends from the shoulder part to the sidewall part through the horizontal reference line of the tire section, and the thickness of the main side wall supporting section gradually decreases from the boundary line of the main shoulder linkage section and the main side wall supporting section to the direction of the sidewall part; the secondary sidewall support section extends from the shoulder part to the sidewall part through the horizontal reference line of the tire section and ends, and the thickness of the secondary sidewall support section gradually decreases from the boundary line of the secondary shoulder linkage section and the secondary sidewall support section to the sidewall part, so that double sidewalls are formed on the sidewall part of the tire, obstacles can be grabbed from different directions, and the traction performance of the sidewall part is improved when the tire runs under low wind pressure.

(4) The boundary of the main tread grounding section and the main shoulder linkage section and the boundary of the secondary tread grounding section and the secondary shoulder linkage section are respectively arranged at the two axial sides of the vertical edge datum line of the tire section, or the boundary of the main tread grounding section and the main shoulder linkage section and the boundary of the secondary tread grounding section and the secondary shoulder linkage section are respectively arranged at the outer axial side of the vertical edge datum line of the tire section, so that the edge effect of double patterns on the shoulder is increased, and the traction performance of the tire under low wind pressure is improved.

(5) The circumferential profiles of the main side wall supporting section and the secondary side wall supporting section are provided with tip portions with a plurality of curved surface profiles, and the tip portions are provided with notch portions or step portions, so that the tip portions can effectively cut into ruts, muddy and the like when the tire runs under low wind pressure and can throw out obstacles along the curved surface profiles of the tip portions along the trend, and the traction performance and the self-cleaning performance of the tire when the tire runs under low wind pressure are improved.

Drawings

FIG. 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention.

Fig. 2 is a partial schematic view of a three-dimensional structure of a shoulder pattern according to a first embodiment of the invention.

Fig. 3 is a partial schematic view of a side view structure of a shoulder pattern according to an embodiment of the invention.

FIG. 4 is a partial cross-sectional view of a tire according to a second embodiment of the present invention.

Fig. 5 is a partial schematic view of a side view structure of a shoulder pattern according to a second embodiment of the invention.

FIG. 6 is a schematic sectional view of A-A' in FIG. 5.

FIG. 7 is a schematic sectional view of B-B' in FIG. 6.

Detailed Description

To more clearly describe the invention, the orientation of the tire is first defined: c.l. represents the tire center plane, c.l. represents the inner side, close to the tire center plane, c.l. represents the outer side, far from the tire center plane; d represents a tire section horizontal datum line, the inner side is close to the tire section horizontal datum line D, and the outer side is far away from the tire section horizontal datum line D; l represents a tire section vertical edge datum line, the vertical edge datum line L close to the tire section represents the inner side, and the vertical edge datum line L far away from the tire section represents the outer side; hereinafter, the vertical direction in fig. 1 and 4 corresponds to the tire radial direction, the horizontal direction corresponds to the tire axial direction, and the direction perpendicular to the paper surface corresponds to the tire circumferential direction.

Example 1

Fig. 1-3 show a schematic structural diagram of a tire according to a first embodiment of the present invention. A pneumatic tire for off-road racing comprises a tire body 100, wherein the tire body 100 comprises a tread part 1, a tire shoulder part 2, a tire side part 3, a tire bead part 4 and a tire body part 5, the tire body part 5 comprises a cord fabric layer 50, and the end part of the cord fabric layer 50 bypasses the tire bead part 4 and is turned outwards. The tread portion 1 is provided with a center region pattern 10 and shoulder patterns 20, the center region pattern 10 is arranged symmetrically at intervals on both sides of a tire center plane C.L to form a center main groove 10a, the shoulder patterns 20 are arranged on the axially outer side of the center region pattern 10, the shoulder patterns 20 are arranged at intervals from the center region pattern 10 to form a center side groove 10b, and the center main groove 10a and the center side groove 10b extend along the tire circumferential direction. In the present embodiment, the center region pattern 10 is designed in accordance with the known pneumatic tire center region for racing, and is arranged as a block pattern formed so as to be arranged at intervals in the circumferential direction and extend in the tire circumferential direction.

The shoulder patterns 20 are formed by arranging shoulder double patterns 200 at intervals in the tire circumferential direction, the shoulder double patterns 200 are formed by a main shoulder pattern 30 and a sub shoulder pattern 40, and the main shoulder pattern 30 and the sub shoulder pattern 40 are arranged at intervals in the tire circumferential direction to form shoulder main grooves 20 a. The shoulder main grooves 20a provide a necessary passage for drainage of water, mud, etc. from the tire, thereby improving traction performance of the tire.

The pneumatic tire for off-road racing is generally driven at low wind pressure even in a zero wind pressure state, and the driving road condition is complicated, and in order to improve the passing property of the pneumatic tire for off-road racing at the time of frequent switching under the obstacle crossing, climbing, sharp turning, etc., the main shoulder pattern 30 is provided as an integral block composed of a main tread ground contact section 31, a main shoulder interlocking section 32, and a main sidewall support section 33, extending from the tread portion 1 to the sidewall portion 3. Wherein, one side of the main shoulder linking section 32 is connected with the main side wall supporting section 33, and the dividing line is a main dividing line 30 a; the other side is connected to the main tread ground segment 31, the dividing line being a main dividing line 30 b. The main tread ground contact section 31 enables the tread portion 1 to be more closely fitted to improve the coating performance of the tread portion 1; the main shoulder linkage section 32 is simultaneously connected with the main tread grounding section 31 and the main sidewall supporting section 33, so that a supporting effect is provided for the main shoulder pattern 30, the shearing of the tire shoulder part 2 when the tire runs at low wind pressure is reduced, the overall pattern rigidity of the main shoulder pattern 30 at low wind pressure even zero wind pressure is enhanced, and the running durability of the main shoulder pattern 30 is improved; the main sidewall support section 33 can keep the sidewall portion 3 upright to avoid collapsing immediately due to low wind pressure or pressure loss. Likewise, the secondary shoulder pattern 40 is provided as an integral rib block consisting of a secondary tread ground-contacting section 41, a secondary shoulder linking section 42 and a secondary sidewall support section 43, extending from the tread portion 1 to the sidewall portion 3. Wherein one side of the secondary shoulder linkage section 42 is connected to the secondary sidewall support section 43, the dividing line being a secondary dividing line 40 a; the other side is connected to the sub-tread ground contact segment 41, and the boundary is a sub-boundary line 40 b. The secondary sidewall support section 43 enables the sidewall portion 3 to remain upright without collapsing immediately due to pressure loss; the sub-tread ground contact section 41 enables the tread portion 1 to be more closely fitted to improve the coating performance of the tread portion 1; the secondary shoulder linkage section 42 connects the secondary tread ground section 41 and the secondary sidewall support section 43 at the same time, provides a support function for the secondary shoulder pattern 40, reduces the shearing of the tire shoulder portion 2 when the tire runs at low wind pressure, strengthens the overall pattern rigidity of the secondary shoulder pattern 40 at low wind pressure even at zero wind pressure, and improves the running durability of the secondary shoulder pattern 40.

The shoulder double pattern 200 composed of the primary shoulder pattern 30 and the secondary shoulder pattern 40 has the axial distance from the radial profile of the primary shoulder linking section 32 to the tire center plane c.l. smaller than the axial distance from the radial profile of the secondary shoulder linking section 42 to the tire center plane c.l. and the axial distance from the radial profile of the primary sidewall support section 33 to the tire center plane c.l. smaller than the axial distance from the radial profile of the secondary sidewall support section 43 to the tire center plane c.l. that is, the profile planes of the primary shoulder pattern 30 and the secondary shoulder pattern 40 constituting the shoulder double pattern 200 do not overlap as viewed from the section direction of the tire. The staggered profile pattern is formed on the tire section, the gripping capacity of the shoulder double patterns 200 under different road conditions such as soft soil, silt, rocks and the like can be strengthened, so that the traction performance of the tire is improved, and when the tire sinks into silt ruts or rugged rock ground gravels, the double-pattern structure of the shoulder double patterns 200 can grip obstacles from different directions, and the obstacle crossing capacity of the tire is improved.

The primary sidewall support section 33 extends from the shoulder portion 2 to the sidewall portion 3 via the tire section horizontal reference line D and gradually decreases in thickness in a direction from the primary boundary line 30a to the sidewall portion 3, and the secondary sidewall support section 43 extends from the shoulder portion 2 to the sidewall portion 3 via the tire section horizontal reference line D and gradually decreases in thickness in a direction from the secondary boundary line 40a to the sidewall portion 3. Since the vicinity of the tire section horizontal reference line D is the region where the deformation of the tire is largest in the sidewall portion 3 under load, and the primary sidewall support section 33 and the secondary sidewall support section 43 of the shoulder double pattern 200 cross the tire section horizontal reference line D, the deformation of the sidewall portion 3 is made to slow down when the tire is driven at low wind pressure. The ratio of the shortest distance d1 from the main end point 30c of the radial profile of the main shoulder pattern 30, which is farthest from the tire center plane C.L. in the axial direction, to the radial outer profile 51 of the carcass portion 5 to the shortest distance d2 from the main end point 30d of the radial profile of the main sidewall support section 33, which is farthest from the tire center plane C.L. in the axial direction, to the radial outer profile 51 of the carcass portion 5 is set to be (2.5-7.0): 1. The ratio of the shortest distance d3 from the next-to-first end point 40c axially farthest from the tire center plane C.L on the radial profile of the secondary shoulder pattern 40 to the radial outer profile 51 of the carcass portion 5 to the shortest distance d4 from the next-to-second end point 40d axially farthest from the tire center plane C.L on the radial profile of the secondary sidewall support section 43 to the radial outer profile 51 of the carcass portion 5 is set to be (5.0-8.5): 1. In the present embodiment, the ratio of the shortest distance d1 to the shortest distance d2 is set to 3.4:1, and the ratio of the shortest distance d3 to the shortest distance d4 is set to 5.9:1, so that it is possible to ensure that the main shoulder pattern 30 and the sub shoulder pattern 40 can form a double sidewall having a step difference of a step, and the main shoulder interlocking section 32 and the main sidewall support sections 33, the sub shoulder interlocking section 42, and the sub sidewall support sections 43 maintain the sidewall support of the tire under interlocking support, reducing the risk of the tire knocking over, thereby ensuring the durability of the tire under low wind pressure. The axial distance d5 between the primary end point 30c on the primary shoulder pattern 30 and the secondary end point 40c on the secondary shoulder pattern 40 is set to 10.0mm to 18.0 mm. In the present embodiment, the axial distance d5 is set to 15.0 mm. If the axial distance d5 is too small, the profile of the shoulder double pattern 200 is not well-arranged, so that the tire has poor gripping capability under different road conditions and the traction performance of the tire is affected; if the axial distance d5 is set too large, the difference in pattern rigidity between the main shoulder pattern 30 and the sub shoulder pattern 40 is too large, increasing the risk of occurrence of root cracks in the shoulder double pattern 200, adversely affecting the durability of the tire.

The axial distance W1 between the main dividing line 30b and the vertical edge reference line L of the tire section on the same side is set to be 4.0% -12.0% of the width DW of the tire section, and the axial distance W2 between the sub dividing line 40b and the vertical edge reference line L of the tire section on the same side is set to be 10.0% -17.0% of the width DW of the tire section. In the present embodiment, the axial distance W1 is set to 10.4% of the tire section width DW, the axial distance W2 is set to 10.7% of the tire section width DW, and the primary dividing line 30b is disposed axially inward of the tire section vertical edge reference line L and the secondary dividing line 40b is disposed axially outward of the tire section vertical edge reference line L. With the arrangement, the attaching areas of the main tread grounding segment 31 in the main shoulder pattern 30 and the secondary tread grounding segment 41 in the secondary shoulder pattern 40 form a fall to increase the edge effect of the shoulder double pattern 200, and the traction performance of the tire in low wind pressure or zero wind pressure running is improved; the primary shoulder linkage sections 32 in the primary shoulder pattern 30 and the secondary shoulder linkage sections 42 in the secondary shoulder pattern 40 also form a reasonable pattern rigidity step, so that the occurrence of root cracks in the shoulder double patterns 200 is avoided, and the durability of the tire is improved.

Of course, fig. 1 illustrates the primary dividing line 30b as being disposed axially inward of the tire section vertical edge reference line L, and the secondary dividing line 40b as being disposed axially outward of the tire section vertical edge reference line L; the main dividing line 30b may be disposed axially outward of the tire section vertical edge reference line L, and the sub dividing line 40b may be disposed axially inward of the tire section vertical edge reference line L. Since the arrangement of the dimensions and the like related to this embodiment is similar to that of the first embodiment, the description thereof is omitted.

Example two

As shown in fig. 4 to 5, the present embodiment is different from the first embodiment in that, in the present embodiment, the main dividing line 30b of the main tread ground contact section 31 and the main shoulder interlocking section 32, and the sub dividing line 40b of the sub tread ground contact section 41 and the sub shoulder interlocking section 42 are disposed axially outside the vertical edge reference line L of the tire section, and the main dividing line 30b is disposed axially inside the sub dividing line 40 b. The axial distance W1 from the main dividing line 30b to the vertical edge reference line L of the same-side tire section was set to 4.2% of the tire section width DW, and the axial distance W2 from the sub dividing line 40b to the vertical edge reference line L of the same-side tire section was set to 16.3% of the tire section width DW. The main shoulder linking section 32 and the sub shoulder linking section 42 can provide a more stable support area for the shoulder double pattern 200, increase the ground contact area of the tire, and form a staggered profile on the tread portion 1 to increase the edge effect of the shoulder double pattern 200, thereby improving the traction performance of the tire in low wind pressure running. When the tire is driven at low wind pressure even at zero wind pressure, the side wall support of the tire is maintained under the interlocking support of the primary shoulder interlocking section 32 and the primary side wall support section 33, the secondary shoulder interlocking section 42 and the secondary side wall support section 43, the risk of the tire unseating is reduced, and the endurance performance of the tire at low wind pressure is ensured.

Since the primary and secondary dividing lines 30b, 40b are disposed on the same axial side of the tire section vertical edge reference line L, the axial distance from the primary dividing line 30a of the primary shoulder interlocking section 32 and the primary side wall support section 33 to the same side tire section vertical edge reference line L and the axial distance from the secondary dividing line 40a of the secondary shoulder interlocking section 42 and the secondary side wall support section 43 to the same side tire section vertical edge reference line L need to be set equal, that is, the primary dividing line 30a overlaps the secondary dividing line 40a as viewed in the tire section direction. If the primary boundary line 30a and the secondary boundary line 40a are not overlapped when viewed from the cross-sectional direction of the tire, the pattern rigidity of the primary tread ground contact section 31 and the primary shoulder portion linkage section 32, and the pattern rigidity of the secondary tread ground contact section 41 and the secondary shoulder portion linkage section 42 are too different, so that the sidewall portion 3 is too thick and heavy, the risk of block root cracking is increased, and the durability of the tire under low wind pressure is not favorable. With this arrangement, the main shoulder interlocking section 32 and the sub shoulder interlocking section 42 can sufficiently exert a weight stabilizing support effect.

The main sidewall support section 33 is provided with a main first tip portion 34 composed of a curved surface profile 341 and a curved surface profile 342 in one side circumferential profile, and is provided with a main second tip portion 35 having a curved surface profile in the other side circumferential profile; the secondary sidewall support section 43 is provided with a secondary tip portion 44 constituted by a curved surface contour 441 and a curved surface contour 442 on one side circumferential contour, and a secondary tip portion 45 having a curved surface contour on the other side circumferential contour, and the primary tip portion 34 and the secondary tip portion 44 are uniform in the bending orientation on the outer side in the circumferential direction of the sidewall portion 3. The curved surface profile 341 of the main tip portion 34 is formed in the circumferential direction of the main sidewall support section 33, and the curved surface profile 342 is formed radially inside the main sidewall support section 33; the curved contour 441 of the next tip portion 44 is formed in the circumferential direction of the secondary sidewall support section 43, and the curved contour 442 is formed radially inward of the secondary sidewall support section 43. When the tire runs at low wind pressure, the main tip part 34 and the secondary tip part 44 cut into obstacles such as ruts and muddy objects towards the same direction, and the obstacles such as the muddy objects and the water are thrown out through the shoulder main groove 20a along the curved surface contour of the main tip part 34 and the secondary tip part 44, so that the obstacles such as the muddy objects are prevented from being attached to the side wall part 3, and the self-cleaning performance and the side wall traction performance of the tire running on the muddy road are improved.

The primary tip 34 has a primary notch portion 36 disposed thereon and the secondary tip 44 has a secondary notch portion 46 disposed thereon. The main sidewall support section 33 and the secondary sidewall support section 43 have profile surfaces that do not overlap to form a double sidewall having a step difference at the sidewall portion 3 when viewed from the cross-sectional direction of the tire, and the main notch portion 36 and the secondary notch portion 46 are provided to increase the edge effect of the double sidewall of the tire, improve the gripping ability when the tire is sunk into a rut such as mud, and improve the sidewall traction performance of the tire.

The notch depths of the main notch portion 36 and the sub notch portion 46 are required to be properly arranged in the main sidewall support section 33 and the sub sidewall support section 43. The notch depth H1 of the main notch portion 36 is set to 15% to 60% of the thickness H1 of the side portion 3, and the notch depth H2 of the sub notch portion 46 is set to 15% to 60% of the thickness H2 of the side portion 3. If the depth of the notch is insufficient, the edge effect of the primary sharp portion 34 and the secondary sharp portion 44 on the sidewall portion 3 is weakened to affect the traction performance of the tire sidewall; if the depth of the notch is too deep, the rigidity of the primary sidewall support section 33 and the secondary sidewall support section 43 is lowered to weaken the durability of the tire. As shown in fig. 6, in the present embodiment, the notch depth H1 of the main notch portion 36 is set to 51% of the thickness H1 of the side portion 3, and the notch depth H2 of the sub notch portion 46 is set to 51% of the thickness H2 of the side portion 3.

The primary second tip portion 35 and the secondary second tip portion 45 are provided as second-order tip portions. Wherein, the main second tip part 35 is composed of a main first tip part 351 and a main second tip part 352; the secondary tip portion 45 is composed of a secondary first-order tip portion 451 and a secondary second-order tip portion 452, and the bending directions of the primary second-order tip portion 35 and the secondary second-order tip portion 45 at the circumferential outer side of the sidewall portion 3 are consistent, so that the edge effect of the double sidewalls of the tire is enhanced, and the obstacle can be grabbed from different directions. When the tire runs at low wind pressure, the main second tip part 35 and the secondary second tip part 45 cut into obstacles such as ruts and muddy in the same direction, and the obstacles are thrown out along the shoulder main groove 20a, so that the adhesion of the muddy obstacles to the sidewall part 3 is avoided, and the self-cleaning performance and the traction performance of the tire when the tire runs at low wind pressure are improved.

In order to further improve the edge effect of the primary and secondary tip portions 35 and 45, a primary step portion 37 is provided on the primary tip portion 35, and a secondary step portion 47 is provided on the secondary tip portion 45. The primary step 37 and the secondary step 47 may be provided as a curved profile having a two-step tip portion, or a curved profile having a one-step tip portion. In the present embodiment, the primary step portion 37 and the secondary step portion 47 are provided as a curved profile having a two-step tip portion to further enhance the edge effect of the primary second tip portion 35 and the secondary second tip portion 45.

The step depths of the primary step 37 and the secondary step 47 are required to be properly arranged in the primary sidewall support section 33 and the secondary sidewall support section 43. The step depth H3 of the primary step portion 37 is 15% to 60% of the thickness H3 of the side wall portion 3, and the step depth H4 of the secondary step portion 47 is 15% to 60% of the thickness H4 of the side wall portion 3. If the step depth is too deep, the rigidity of the main sidewall support section 33 and the secondary sidewall support section 43 is affected, the sidewall support performance of the tire during low wind pressure driving is affected, and even the block falling on rock road conditions can occur, so that the durability of the tire is insufficient; if the step depth is insufficient, the edge effect of the primary second tip portion 35 and the secondary second tip portion 45 is weakened. As shown in fig. 7, in the present embodiment, the step depth H3 of the primary step portion 37 is 20% of the thickness H3 of the existing sidewall portion 3, and the step depth H4 of the secondary step portion 47 is 20% of the thickness H4 of the existing sidewall portion 3.

The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A pneumatic tire for cross-country racing comprises a tire body, the tire body comprises a tread portion, a shoulder portion, a sidewall portion, a bead portion and a carcass portion, the tread portion is provided with a central region pattern and a shoulder pattern, and the pneumatic tire is characterized in that,

the shoulder double patterns are formed by arranging shoulder double patterns at intervals along the circumferential direction of the tire, the shoulder double patterns comprise main shoulder patterns and secondary shoulder patterns, the main shoulder patterns and the secondary shoulder patterns are arranged at intervals along the circumferential direction of the tire to form shoulder main grooves, and the main shoulder patterns and the secondary shoulder patterns extend from the tread part to the sidewall part;

the main shoulder pattern includes a main tread ground section, a main shoulder linking section, and a main sidewall support section, the main shoulder linking section being connected to the main tread ground section on one side and to the main sidewall support section on the other side, the main sidewall support section terminating from the shoulder portion to the sidewall portion via a tire section horizontal reference line, the main sidewall support section having a thickness gradually decreasing from a boundary line of the main shoulder linking section and the main sidewall support section to the sidewall portion;

the secondary shoulder pattern comprises a secondary tread grounding section, a secondary shoulder linkage section and a secondary side wall supporting section, one side of the secondary shoulder linkage section is connected with the secondary tread grounding section, the other side of the secondary shoulder linkage section is connected with the secondary side wall supporting section, the secondary side wall supporting section extends from the shoulder part to the sidewall part through a tire section horizontal datum line and is terminated, and the thickness of the secondary side wall supporting section is gradually reduced from the boundary line of the secondary shoulder linkage section and the secondary side wall supporting section to the sidewall part;

the shoulder linking sections and the sidewall support sections constituting the shoulder double patterns do not overlap in profile when viewed from the tire cross-sectional direction.

2. A pneumatic cross-country tire according to claim 1, wherein the boundary between the main tread ground contact section and the main shoulder link section is disposed axially inward of the vertical edge reference line of the tire section, and the boundary between the sub tread ground contact section and the sub shoulder link section is disposed axially outward of the vertical edge reference line of the tire section.

3. A pneumatic cross-country tire according to claim 1, wherein the boundary between the main tread ground contact section and the main shoulder link section is disposed axially outward of the vertical edge reference line of the tire section, and the boundary between the sub tread ground contact section and the sub shoulder link section is disposed axially inward of the vertical edge reference line of the tire section.

4. A pneumatic cross-country tire according to claim 1, wherein the boundary between the main tread ground contact section and the main shoulder link section is disposed axially outside the vertical edge reference line of the tire section, and the boundary between the sub tread ground contact section and the sub shoulder link section is disposed axially outside the vertical edge reference line of the tire section;

the axial distance from the boundary of the main shoulder linkage section and the main side wall supporting section to the vertical edge reference line of the tire section on the same side is equal to the axial distance from the boundary of the secondary shoulder linkage section and the secondary side wall supporting section to the vertical edge reference line of the tire section on the same side.

5. A pneumatic cross-country tire according to any one of claims 2 to 4, wherein the axial distance between the axially most distal point of the radial profile of the primary shoulder pattern from the center plane of the tire and the axially most distal point of the radial profile of the secondary shoulder pattern from the center plane of the tire is from 10.0mm to 18.0 mm.

6. A pneumatic tire for off-road racing according to claim 5, wherein the axial distance from the boundary between the main tread ground contact section and the main shoulder linkage section to the vertical edge reference line of the tire section on the same side is 4.0% to 12.0% of the width of the tire section, and the axial distance from the boundary between the sub tread ground contact section and the sub shoulder linkage section to the vertical edge reference line of the tire section on the same side is 10.0% to 17.0% of the width of the tire section.

7. A pneumatic tire for cross-country racing according to claim 6, wherein the ratio of the shortest distance from the farthest point on the main shoulder pattern radial profile axially from the tire center plane to the radial outer profile of the carcass portion to the shortest distance from the farthest point on the main sidewall support section radial profile axially from the tire center plane to the radial outer profile of the carcass portion is (2.5-7.0): 1;

the ratio of the shortest distance from the farthest end point axially away from the tire central plane to the radial outer contour of the tire body part on the radial profile of the secondary shoulder pattern to the shortest distance from the farthest end point axially away from the tire central plane to the radial outer contour of the tire body part on the radial profile of the secondary side wall supporting section is (5.0-8.5): 1.

8. A pneumatic off-road racing tire as claimed in claim 7, wherein the one-side circumferential profile of the primary sidewall supporting section is provided with a primary one-peak portion having a plurality of curved surface profiles, and the one-side circumferential profile of the secondary sidewall supporting section is provided with a secondary one-peak portion having a plurality of curved surface profiles, the primary one-peak portion and the secondary one-peak portion being curved toward the outside in the circumferential direction of the sidewall portion in a uniform orientation.

9. A pneumatic tire for off-road racing according to claim 8, wherein the main tip portion is provided with a main notch portion, and the notch depth of the main notch portion is 15-60% of the thickness of the tire side portion; the secondary sharp portion is provided with a secondary notch portion, and the notch depth of the secondary notch portion is 15% -60% of the thickness of the tire side portion.

10. A pneumatic tire for off-road racing according to claim 9, wherein the side of the circumferential contour of the primary sidewall support section at which the primary peak portion is provided with a primary peak portion having a plurality of curved surface contours, and the side of the circumferential contour of the secondary sidewall support section at which the secondary peak portion is provided with a secondary peak portion having a plurality of curved surface contours, the primary peak portion and the secondary peak portion having the same curvature orientation at the outer circumferential side of the sidewall portion;

the main two-point part is provided with a main step part, the step depth of the main step part is 15% -60% of the thickness of the side portion where the main step part is located, the secondary two-point part is provided with a secondary step part, and the step depth of the secondary step part is 15% -60% of the thickness of the side portion where the secondary step part is located.

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