JP6930130B2 - Pneumatic tires - Google Patents

Description

The present invention relates to a pneumatic tire.

In order to improve drainage performance, a pneumatic tire provided with a plurality of horizontal main grooves inclined with respect to the tire circumferential direction from the ground contact end of the tread is known (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2005-153654

The pneumatic tire described in Patent Document 1 has room for improvement in improving drainage performance while maintaining uneven wear resistance and steering stability performance.

The present invention has been made in view of the above, and an object of the present invention is to provide a pneumatic tire capable of improving drainage performance and not deteriorating uneven wear resistance and steering stability performance. ..

In order to solve the above-mentioned problems and achieve the object, the pneumatic tire according to an embodiment of the present invention is provided on both the left and right sides in the tire width direction with reference to the tire equatorial line, and extends in the tire circumferential direction2. The two center main grooves, the outermost main groove extending outward in the tire width direction of each of the two center main grooves in the tire circumferential direction, and the outermost main groove communicating from the tire contact end to the outermost main groove, and further to the center main groove. It is provided with a first series of lug grooves in contact with each other, and the two center main grooves have an amplitude in the tire width direction, and by being sandwiched between the two center main grooves, a wavy center land portion is formed on the tire equatorial line. The groove width of the center main groove is formed and changes depending on the position in the tire circumferential direction, and the groove width of the center main groove is the other at the confluence portion of the center main groove and the first series lug groove. The second land portion formed between the center main groove and the outermost main groove is divided in the tire circumferential direction by arranging the first series of lug grooves in the tire circumferential direction, which is narrower than the portion. , An arc-shaped block is formed in which a part of the edge is a curved portion.

When the distance at which the outermost end of the outermost main groove in the tire width direction is separated from the tire equatorial line is L2 and half of the tread deployment width is TW, the ratio L2 / TW is in the range of 0.50 or more and 0.60 or less. Is preferable.

It is preferable that the groove width of the outermost main groove is wider than the groove width of the center main groove, and the groove width of the outermost main groove is wider than the groove width of the first series lug groove.

When the groove width of the outermost main groove is W1 and half of the tread development width is TW, the ratio W1 / TW is preferably in the range of 0.1 or more and 0.2 or less.

The center main groove is formed in a see-through structure in the tire circumferential direction, and the distance at which the outermost edge of the center main groove in the tire width direction is separated from the tire equatorial line is L1, and half of the tread deployment width is TW. / TW is preferably in the range of 0.15 or more and 0.25 or less.

When the amplitude of the center main groove in the tire width direction is W and half of the tread expansion width is TW, the ratio W / TW is in the range of 0.04 or more and 0.10 or less, and the repeating pitch length of the center main groove. It is preferable that P is in the range of 60 mm or more and 100 mm or less.

The two center main grooves are preferably arranged so that the maximum positions of the amplitudes in the tire width direction are out of phase with each other within a range of ± 20 °.

In the first series of lug grooves, a virtual line connecting the maximum amplitude position inside the center main groove in the tire width direction and the maximum amplitude position outside the center main groove in the tire width direction, and the tire of the center main groove. The angle α formed by the virtual line connecting the maximum amplitude positions on the outer side in the width direction is 20 ° or more and 50 ° or less, and the maximum amplitude position on the outer side in the tire width direction of the center main groove and the tire ground contact end in the lug groove. It is preferable that the angle β formed by the virtual line connecting the center position of the width of the first series of lug grooves in the tire circumferential direction and the virtual line along the tire circumferential direction is 50 ° or more and 80 ° or less. ..

The groove width of the center main groove is preferably wider than the groove width of the first series lug groove.

Between the first series of communication lug grooves, a second communication lug groove that terminates in the middle of the second land portion between the tire ground contact end and the center main groove and the outermost main groove may be further included. preferable.

It is preferable that the width of the second communication lug groove narrows from the tire ground contact end toward the end in the second land portion.

The ratio L3 / TW is 0.15 or more and 0.20 or less when the distance from the tire equatorial line is L3 and half of the tread deployment width is TW for the terminal position in the second land portion of the second communication lug groove. Is preferable.

According to the pneumatic tire according to the present invention, it is possible to improve the drainage performance and prevent the uneven wear resistance performance and the steering stability performance from being deteriorated.

FIG. 1 is a cross-sectional view of a meridian showing a pneumatic tire according to the first embodiment of the present invention. FIG. 2 is a plan view showing a tread portion of the pneumatic tire shown in FIG. FIG. 3 is a diagram showing a part of the groove of the tread portion omitted in FIG. 2. FIG. 4 is a diagram showing a part of the groove of the tread portion omitted in FIG. 2. FIG. 5 is a plan view showing a tread portion of a pneumatic tire according to another embodiment of the present invention. FIG. 6 is a diagram showing a tread pattern of a comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. This embodiment does not limit the invention. In addition, the components of this embodiment include those that can be easily replaced by those skilled in the art, or those that are substantially the same. The plurality of modifications described in this embodiment can be arbitrarily combined within a range self-evident by those skilled in the art. In the description of each of the following figures, the same or equivalent components as those of the other figures are designated by the same reference numerals, and the description thereof will be simplified or omitted.

[First Embodiment]
FIG. 1 is a cross-sectional view of a meridian showing a pneumatic tire according to the first embodiment of the present invention. FIG. 1 shows a cross-sectional view of a one-sided region in the tire radial direction. Further, FIG. 1 shows a radial tire for a passenger car as an example of a pneumatic tire 1 (hereinafter, appropriately referred to as a tire 1). FIG. 2 is a plan view showing a tread portion 3 of the pneumatic tire 1 shown in FIG.

In FIG. 1, the cross section in the tire meridian direction refers to a cross section when a tire is cut on a plane including a tire rotation axis (not shown). Further, the symbol CL is a tire equatorial plane, and refers to a plane that passes through the center point of the tire in the tire rotation axis direction and is perpendicular to the tire rotation axis. Further, the tire radial direction means a direction perpendicular to the tire rotation axis. In FIG. 2, the tire width direction means a direction parallel to the tire rotation axis, and the tire circumferential direction means a direction around the tire rotation axis. The tire equatorial line is a line on the tire equatorial plane CL along the tire circumferential direction of the pneumatic tire 1. In the present embodiment, the tire equatorial line is designated by the same code "CL" as the tire equatorial plane.

The pneumatic tire 1 has an annular structure centered on a tire rotation axis, and has a pair of bead cores 11 and 11, a pair of bead fillers 12 and 12, a carcass layer 13, a belt layer 14, and a tread rubber 2. , A pair of sidewall rubbers 16 and 16, and a pair of rim cushion rubbers 17 and 17. Further, an inner liner 15 is formed along the carcass layer 13 on the inside of the carcass layer 13 or on the inner side of the carcass layer 13 in the pneumatic tire 1.

The pair of bead cores 11 and 11 is an annular member formed by bundling a plurality of bead wires, and constitutes the cores of the left and right bead portions 10. The pair of bead fillers 12 and 12 are arranged on the outer periphery of the pair of bead cores 11 and 11 in the tire radial direction to form the bead portion 10.

The carcass layer 13 has a single-layer structure composed of one carcass ply or a multi-layer structure formed by laminating a plurality of carcass plies, and is bridged between the left and right bead cores 11 and 11 in a toroidal shape to form a tire skeleton. Constitute. Further, both ends of the carcass layer 13 are wound and locked outward in the tire width direction so as to wrap the bead core 11 and the bead filler 12. The carcass ply of the carcass layer 13 is formed by coating a plurality of carcass cords made of steel or an organic fiber material (for example, aramid, nylon, polyester, rayon, etc.) with a coated rubber and rolling them.

The belt layer 14 is formed by laminating a pair of intersecting belts 141 and 142 and a belt cover 143, and is arranged so as to be hung around the outer periphery of the carcass layer 13. The pair of crossing belts 141 and 142 are formed by coating a plurality of belt cords made of steel or an organic fiber material with coated rubber and rolling them. Further, the pair of crossing belts 141 and 142 have differently signed belt angles (defined as inclination angles in the longitudinal direction of the belt cord with respect to the tire circumferential direction), and the longitudinal directions of the belt cords intersect each other. Are stacked. The belt cover 143 is formed by rolling a plurality of cords made of steel or an organic fiber material coated with a coated rubber. Further, the belt covers 143 are laminated and arranged on the outer side in the tire radial direction of the cross belts 141 and 142.

The tread rubber 2 is arranged on the outer periphery of the carcass layer 13 and the belt layer 14 in the tire radial direction to form the tread portion 3 of the tire. The pair of sidewall rubbers 16 and 16 are arranged outside the carcass layer 13 in the tire width direction, respectively, to form the left and right sidewall portions 6. The pair of rim cushion rubbers 17 and 17 are arranged inside the left and right bead cores 11 and 11 and the rewinding portion of the carcass layer 13 in the tire radial direction, respectively, and form contact surfaces of the left and right bead portions 10 with respect to the rim flange.

[Tread pattern]
As shown in FIG. 2, the pneumatic tire 1 of this example has a center land divided into five rows by four circumferential main grooves 20 extending in the tire circumferential direction and four circumferential main grooves 20. The tread portion 3 is provided with a portion 31, a second land portion 32, a shoulder land portion 33, a plurality of first communication lug grooves 41, a plurality of second communication lug grooves 42, and a center lug groove 51.

The tread portions 3 are arranged at predetermined intervals in the tire circumferential direction, and include a plurality of first communication lug grooves 41 that penetrate the second land portion 32 and the shoulder land portion 33 in the tire width direction, and a plurality of second communication lug grooves. It has 42 and. Each of the second land portion 32 and the shoulder land portion 33 is divided into a circumferential main groove 20, a first communication lug groove 41, and a second communication lug groove 42 to form a block row.

The circumferential main groove 20 is a circumferential groove having a wear indicator indicating the end of wear, and generally has a groove width of 5.0 mm or more and a groove depth of 7.5 mm or more. The lug groove means a lateral groove having a groove width of 2.0 mm or more and a groove depth of 3.0 mm or more.

The circumferential main groove 20 includes a center main groove 21 extending in the tire circumferential direction near the tire equatorial line CL and an outermost main groove extending in the tire circumferential direction outside the center main groove 21 in the tire width direction. 22 and is included. As shown in FIG. 2, the center main groove 21 is a main groove extending in the tire circumferential direction and having a wavy shape. "Wavy shape" means having an amplitude in the tire width direction. In this example, the center main groove 21 is a sinusoidal main groove. The sinusoidal shape is a shape that extends in the tire circumferential direction and periodically changes the distance in the tire width direction from the equatorial line CL according to the position in the tire circumferential direction. The sinusoidal shape also includes a case where the period of change of the distance in the tire width direction is not completely constant and has an error, and a case where the wavelength in the tire circumferential direction is not completely constant and has an error. Further, the shape is not limited to the sinusoidal shape, and the center main groove 21 may have a zigzag shape extending in the tire circumferential direction while being bent or curved in the tire width direction (not shown).

In FIG. 2, reference numeral T is a tire ground contact end. The tire ground contact end T is a portion where the tire 1 is rim-assembled on a regular rim, filled with a regular internal pressure, placed vertically on a flat surface, and the tread portion 3 touches the ground when a normal load is applied. Refers to the end of the tire in the width direction.

Further, in the configuration of FIG. 2, the tread portion 3 has a similar tread pattern on the left and right sides centering on the tire equatorial plane CL. Not limited to this, the tread portion 3 may have the tread pattern shown in FIG. 2 on only one of the left and right sides with the tire equatorial plane CL as the center, and may have another tread pattern on the other side (not shown).

The groove width is measured as the maximum value of the distance between the left and right groove walls at the groove opening in a no-load state in which the tire 1 is mounted on the specified rim and the specified internal pressure is filled. In a configuration in which the land portion has a notch or a chamfered portion at the edge portion, the groove width is set based on the intersection of the tread tread and the extension line of the groove wall in a cross-sectional view with the groove length direction as the normal direction. Be measured. Further, in the configuration in which the grooves extend in a zigzag shape or a wavy shape in the tire circumferential direction, the groove width is measured with reference to the center line of the amplitude of the groove wall.

The groove depth is measured as the maximum value of the distance from the tread tread to the groove bottom in a no-load state in which the tire 1 is mounted on the specified rim and the specified internal pressure is filled. Further, in a configuration in which the groove has a partially uneven portion or a sipe on the groove bottom, the groove depth is measured by excluding these.

A "regulated rim" is a rim that is defined for each tire 1 in the standard system including the standard based on the tire 1, and is a standard rim for JATTA, "DesignRim" for TRA, and ETRTO. If there is, it is "Measuring Rim". However, if the tire 1 is a tire mounted on a new car, a genuine wheel to which the tire 1 is assembled is used.

The "specified internal pressure" is the air pressure defined for each tire 1 in the standard system including the standard based on the tire 1, and is the maximum air pressure for JATTA and the table "TIRE LOAD LIMITED AT VARIOUS" for TRA. The maximum value described in "COLD INFLATION PRESSURES", and in the case of ETRTO, it is "INFRATION PRESSURE". However, when the tire 1 is a tire mounted on a new vehicle, the air pressure displayed on the vehicle is used.

The "specified load" is the load defined for each tire 1 in the standard system including the standard based on the tire 1, and is the maximum load capacity for JATTA and the table "TIRE LOAD LIMITED AT" for TRA. The maximum value described in "VARIOUS COLD INFLATION PRESSURES", and in the case of ETRTO, it is "LOAD CAPACITY". However, when the tire 1 is a passenger car, the load corresponds to 88 [%] of the above load. When the tire 1 is a tire mounted on a new vehicle, the wheel load is obtained by dividing the front and rear axle load described in the vehicle verification of the vehicle by the number of tires.

In FIG. 2, one end of the center lug groove 51 is thicker than the other end. The thick end of the center lug groove 51 communicates with the extension portion 21E provided on the tire equatorial line CL side of the center main groove 21, and the thin other end of the center lug groove 51 communicates with another center lug groove arranged in the tire circumferential direction. It communicates with the thick end of 51. Further, in the second land portion 32, between the center main groove 21 and the outermost main groove 22, the tire circumference communicates with the outermost main groove 22 outward in the tire width direction from the maximum amplitude portion of the center main groove 21. The first communication lug groove 41 is arranged so as to line up in the direction. Therefore, the second land portion 32 is divided in the tire circumferential direction by the first series of lug grooves 41, and a plurality of arc-shaped blocks 32a are arranged side by side in the tire circumferential direction.

In FIG. 2, the arrow Y indicates the rotation direction of the pneumatic tire 1. The upper side of FIG. 2 is the first-come-first-served side (stepping side) to the road surface, and the lower side of FIG. 2 is the second-arriving side (kicking side) to the road surface.

3 and 4 are views showing, in FIG. 2, a part of the groove of the tread portion 3 is omitted.

As shown in FIG. 3, the pneumatic tire 1 communicates with one or more center main grooves 21 from the tire equatorial line CL on at least one of the left and right sides in the tire width direction, and from the tire ground contact end T to the center main groove 21. It is provided with a series of lug grooves 41. The center main groove 21 has an amplitude in the tire width direction. The first series lug groove 41 is in contact with the center main groove 21. Since the pneumatic tire 1 has such a configuration, the water in the center land portion 31 can be effectively discharged to the outside of the tread pattern of the tread portion 3.

As shown in FIG. 3, the distance of the center main groove 21 from the tire equatorial line CL in the tire width direction changes periodically depending on the extending direction, that is, the position in the tire circumferential direction. The position where the first series lug groove 41 is in contact with the center main groove 21 is the position where the distance between the center main groove 21 and the tire equatorial line CL in the tire width direction is the maximum (hereinafter referred to as the maximum amplitude position), and the center main. The position where the distance between the groove 21 and the tire equatorial line CL in the tire width direction is the minimum (hereinafter referred to as the minimum amplitude position), the position intermediate between the maximum amplitude position and the minimum amplitude position (hereinafter referred to as the intermediate amplitude position), Can be considered. Of the maximum amplitude position, the minimum amplitude position, and the intermediate amplitude position, at the maximum amplitude position as shown in FIG. 3, the first series lug groove 41 comes into contact with the center main groove 21 to tread the water in the center land portion 31. It can be more effectively discharged to the outside of the tread pattern of the part 3.

As shown in FIG. 3, the pneumatic tire 1 is provided on both the left and right sides in the tire width direction with reference to the tire equatorial line CL, and has two center main grooves 21 extending in the tire circumferential direction and two center mains. The outermost main groove 22 extending outward in the tire width direction of each of the grooves 21 and the first series of lug grooves 41 communicating with the outermost main groove 22 from the tire ground contact end T and further in contact with the center main groove 21. And have. The two center main grooves 21 have an amplitude in the tire width direction, and the wave-shaped center land portion 31 is formed on the tire equatorial line CL by being sandwiched between the two center main grooves 21. Further, by arranging the first series of lug grooves 41 in the tire circumferential direction, the second land portion 32 formed between the center main groove 21 and the outermost main groove 22 is divided in the tire circumferential direction to form an arc shape. Block 32a is formed. According to such a configuration, the water in the center portion can be effectively discharged, and the steering stability performance can be improved.

Here, as shown in FIG. 4, when the distance at which the outermost end of the outermost main groove 22 in the tire width direction is separated from the tire equatorial line CL is L2, and half of the tread deployment width is TW, the ratio is L2 / TW. Is preferably in the range of 0.50 or more and 0.60 or less. When the ratio L2 / TW is less than 0.50, the rigidity of the second land portion 32 becomes weak and the steering stability performance deteriorates. On the other hand, when the ratio L2 / TW is larger than 0.60, the drainage performance deteriorates. When the ratio L2 / TW is in the above range, the steering stability performance is not deteriorated and the drainage performance is not deteriorated.

Further, in the pneumatic tire 1, the groove width of the outermost main groove 22 is wider than the groove width of the center main groove 21, and the groove width of the outermost main groove 22 is wider than the groove width of the first series lug groove 41. Is also preferable. According to this configuration, the rigidity balance of the second land portion 32 is particularly good, and it is possible to improve the uneven wear resistance performance while improving the drainage performance.

In the pneumatic tire 1, when the groove width of the outermost main groove 22 is W1 and half of the tread development width is TW, the ratio W1 / TW is preferably in the range of 0.1 or more and 0.2 or less. If the ratio W1 / TW is less than 0.1, the drainage performance deteriorates. On the other hand, when the ratio W1 / TW is larger than 0.2, the steering stability performance deteriorates. If the ratio W1 / TW is in the above range, the drainage performance does not deteriorate and the steering stability performance does not deteriorate.

Further, the pneumatic tire 1 preferably has a center main groove 21 formed in a see-through structure in the tire circumferential direction. The see-through structure is a structure in which a continuous space is formed when the center main groove 21 is projected in the tire circumferential direction. More specifically, even if the center main groove 21 has a sinusoidal shape as shown in FIG. 3, a see-through portion remains at the center position (indicated by the alternate long and short dash line 210) in the tire width direction. There is. Further, as shown in FIG. 4, the pneumatic tire 1 has a ratio L1 when the outermost edge of the center main groove 21 in the tire width direction is separated from the tire equatorial line CL by L1 and half of the tread deployment width is TW. / TW is preferably in the range of 0.15 or more and 0.25 or less.

In the pneumatic tire 1, if the ratio L1 / TW is less than 0.15, uneven wear of the center land portion 31 is likely to occur. On the other hand, if the ratio L1 / TW is larger than 0.25, the drainage performance deteriorates. The tread deployment width TW is the tread deployment width TW at both ends in the tire width direction in the development view of the tread portion 3 when the pneumatic tire 1 is mounted on the specified rim and a specified internal pressure is applied and no load is applied. It is a straight line distance.

In FIG. 4, the pneumatic tire 1 has a ratio W / TW in the range of 0.04 or more and 0.10 or less when the amplitude of the center main groove 21 in the tire width direction is W and half of the tread deployment width is TW. It is preferable that the repeating pitch length P of the center main groove 21 is in the range of 60 mm or more and 100 mm or less. When the ratio W / TW is less than 0.04, the drainage performance can be improved, but uneven wear is likely to occur. On the other hand, when the ratio W / TW is larger than 0.10, the drainage performance deteriorates. Further, when the pitch length P of the center main groove 21 is larger than 100 mm, the drainage performance can be improved, but uneven wear is likely to occur. On the other hand, when the pitch length P is less than 60 mm, uneven wear is likely to occur. The number of amplitudes, that is, the number of pitches of the center main grooves 21 arranged in the tire circumferential direction is preferably 15 or more and 30 or less, for example.

The pneumatic tire 1 has two center main grooves 21, and the two center main grooves 21 are arranged so that the maximum positions of the amplitudes in the tire width direction are deviated from each other by + 20 ° or less and -20 ° or more. Is preferable. That is, the two center main grooves 21 are arranged so that the phase difference PH at the maximum position of the amplitude in the tire width direction is shifted within a range of ± 20 °. When the amount of phase shift between the center main grooves 21 exceeds the range of ± 20 °, the water in the center land portion 31 cannot be effectively discharged to the outside of the tread pattern of the tread portion 3.

The pneumatic tire 1 has a virtual line connecting the maximum amplitude position inside the center main groove 21 in the tire width direction and the maximum amplitude position outside the center main groove 21 in the tire width direction in the first series of lug grooves 41. It is preferable that the angle α formed by the virtual line connecting the maximum amplitude positions on the outer side of the center main groove 21 in the tire width direction is 20 ° or more and 50 ° or less.

Further, the pneumatic tire 1 has a maximum amplitude position outside the center main groove 21 in the tire width direction and a tire circumferential direction of the first series lug groove 41 at the tire ground contact end T in the first series lug groove 41. It is preferable that the angle β formed by the virtual line connecting the center position of the width and the virtual line along the tire circumferential direction is 50 ° or more and 80 ° or less.

Regarding the first series of lug grooves 41 connected to the center main groove 21, the degree of bending inside the center main groove 21 and the degree of bending outside the center main groove 21 are defined in the above angle range, and in particular, the first The rigidity balance of the land portion 32 is good, and it is possible to improve the uneven wear resistance performance while improving the drainage performance.

In the pneumatic tire 1, the groove width of the center main groove 21 is preferably wider than the maximum groove width of the first series through lug groove 41 over the entire center main groove 21. Therefore, the groove width of the first series lug groove 41 is narrower than the groove width of the center main groove 21, and the rigidity of the portion where the first series lug groove 41 is formed can be ensured. As a result, the rigidity balance of the second land portion 32 is particularly improved, and the uneven wear resistance performance can be improved while improving the drainage performance.

In the pneumatic tire 1, the groove width of the center main groove 21 changes depending on the position in the tire circumferential direction, and the confluence portion between the center main groove 21 and the first series lug groove 41 may be narrower than the other portions. preferable. Specifically, it is preferable that the length L4 shown in FIG. 4 is shorter than the other portions. For example, the length L4 may be 90% or more and 95% or less of the maximum groove width of the center main groove 21. In this way, at the confluence of the center main groove 21 and the first series of lug grooves 41, the groove width of the center main groove 21 is narrower than the other parts, so that the center land portion 31 and the second land portion 32 The rigidity balance is good, and it is possible to improve the uneven wear resistance while improving the drainage performance.

The pneumatic tire 1 further includes a second communication lug groove 42 that terminates between the first series of communication lug grooves 41 in the middle of the second land portion 32 from the tire ground contact end T. By the presence of the second communication lug groove 42 in this way, it is possible to improve the drainage performance and prevent the uneven wear performance from being deteriorated.

The width of the second communication lug groove 42 narrows from the tire ground contact end T toward the end in the second land portion 32. With the presence of the second communication lug groove 42 in this way, the rigidity balance of the shoulder land portion 33 and the second land portion 32 is particularly good, and it is possible to improve the uneven wear resistance performance while improving the drainage performance.

The pneumatic tire 1 has a ratio of L3 / TW of 0 when the distance from the tire equatorial line CL is L3 and half of the tread deployment width is TW at the terminal position in the second land portion 32 of the second communication lug groove 42. It is preferably .15 or more and 0.20 or less. When the ratio L3 / TW is less than 0.15, uneven wear of the center land portion 31 is likely to occur. On the other hand, when the ratio L3 / TW is larger than 0.20, the drainage performance deteriorates.

The pneumatic tire 1 preferably has a ratio W2 / CW of the width W2 of the center land portion 31 in the tire width direction to the distance between the ground contact ends T, that is, the ground contact width CW, of 0.15 or more and 0.20 or less. When the ratio W2 / CW is less than 0.15, uneven wear of the center land portion 31 is likely to occur. On the other hand, when the ratio W2 / CW is larger than 0.20, the drainage performance deteriorates.

[Other Embodiments]
FIG. 5 is a plan view showing a tread portion 3 of a pneumatic tire 1 according to another embodiment of the present invention. As shown in FIG. 5, the pneumatic tire 1 of this example has a land portion divided into four rows by three circumferential main grooves 20 extending in the tire circumferential direction and three circumferential main grooves 20. The tread portion 3 is provided with 32 and 33, a plurality of first series lug grooves 41, and a plurality of second communication lug grooves 42.

The circumferential main groove 20 includes a center main groove 21 and an outermost main groove 22 extending in the tire circumferential direction outside the center main groove 21 in the tire width direction. As shown in FIG. 5, the sinusoidal center main groove 21 may be located on the tire equatorial line CL.

[Example]
Tables 1 and 2 are tables showing the results of performance tests of pneumatic tires according to the embodiment of the present invention. In this performance test, drainage performance was evaluated for multiple types of test tires. The vehicle used for the evaluation is Super-formula Dallara SF14. The size of the front tire was 250 / 620R13, the size of the rear tire was 360 / 620R13, and the drainage performance was confirmed under the following conditions. The air pressure is 120 kPa for the front tires and 130 kPa for the rear tires before the vehicle travels. The weight of the evaluation vehicle is 660 kg when the driver is on board. The evaluation course is the Okayama International Circuit (3.703km / lap). The number of evaluation laps is 34 Lap (34 Lap × 3.703 km = 125.902 km). The weather on the circuit is rainy.

The pneumatic tires 1 of Examples 1 to 19 have the configurations shown in FIGS. 1 to 4. The pneumatic tires 1 of Examples 1 to 19 are provided on both the left and right sides in the tire width direction with reference to the tire equatorial line CL, and have two center main grooves 21 extending in the tire circumferential direction and two centers. The outermost main groove 22 extending outward in the tire width direction of each of the main grooves 21 in the tire circumferential direction, and the first series of lug grooves that communicate with the outermost main groove 22 from the tire ground contact end T and further contact the center main groove 21. It is equipped with 41. The positions where the first series lug groove 41 contacts the center main groove 21 are the minimum amplitude position in Examples 1 to 4, the intermediate amplitude position in Examples 5 to 6, and the maximum position in Examples 6 to 19. Amplitude position.

The pneumatic tire 1 has a ratio L2 / TW of 0.04 for Example 1, 0.70 for Example 5, 0. For Examples 2 to 4 and 6 to 19. It is a value in the range of 50 or more and 0.60 or less. The pneumatic tire 1 has a ratio W1 / TW of 0.05 for Examples 1 to 2, 0.30 for Example 5, and Examples 3 to 4 and 6 to 19 for Example 5. Is a value in the range of 0.1 or more and 0.2 or less.

In the pneumatic tire 1 of Examples 1 to 19, the center main groove 21 is formed in a see-through structure in the tire circumferential direction, and the ratio L1 / TW is 0.12 for Examples 1 to 3. The values of Examples 4 to 19 are in the range of 0.15 or more and 0.25 or less.

The pneumatic tire 1 has a ratio W / TW of 0.02 for Examples 1 to 4, 0.15 for Example 5, and 0.04 or more and 0.10 for Examples 6 to 19. It is a value within the following range. Further, in the pneumatic tire 1, the repeating pitch length P of the center main groove 21 is 50 mm for Examples 1 to 4, 110 mm for Examples 5 to 6, and Examples 7 to 19 for the pneumatic tire 1. It is a value within the range of 60 mm or more and 100 mm or less.

In the pneumatic tire 1, the phase difference PH at the maximum position of the amplitude of the two center main grooves 21 in the tire width direction is −40 ° for Examples 1 to 4 and +30 for Examples 5 to 6. °, values within the range of ± 20 ° for Examples 7 to 19.

Further, the pneumatic tire 1 has an angle α of 20 ° or more and 50 ° or less and an angle β of 50 ° or more and 80 ° or less in Examples 1 to 19.

In the pneumatic tire 1, the groove width of the center main groove 21 is narrower than the groove width of the first series through lug groove 41 in Examples 1 to 4, and the center main groove 21 in Examples 5 to 19 The groove width of is wider than the groove width of the first series of lug grooves 41. In the pneumatic tire 1, in the first to second embodiments, the groove width of the outermost main groove 22 is narrower than the groove width of the center main groove 21, and the groove width of the outermost main groove 22 is the first series of lugs. It is narrower than the groove width of the groove 41. In the pneumatic tire 1, in the third embodiment, the groove width of the outermost main groove 22 is wider than the groove width of the center main groove 21, and the groove width of the outermost main groove 22 is the groove of the first series lug groove 41. Narrower than the width. In the pneumatic tire 1, from Examples 4 to 19, the groove width of the outermost main groove 22 is wider than the groove width of the center main groove 21, and the groove width of the outermost main groove 22 is the first series. It is wider than the groove width of the lug groove 41.

The pneumatic tire 1 has a second communication lug groove 42, and the shape of the second communication lug groove 42 tapers toward the outer end of the tread pattern in Examples 1 to 4, and is carried out from Example 5. Example 19 tapers towards the center.

As a comparative example, a tire having the tread pattern of FIG. 6 was prepared. FIG. 6 is a diagram showing a tread pattern of a comparative example. As shown in FIG. 6, in the tread pattern of the comparative example, the main grooves 20 extending in the circumferential direction are all straight and not sinusoidal. The tread pattern of the comparative example has a communication lug groove 40 corresponding to the first communication lug groove 41 and does not have a lug groove corresponding to the second communication lug groove 42. The tread pattern of the comparative example has a ratio L2 / TW of 0.27, a ratio W1 / TW of 0.10, and a ratio of L1 / TW of 0.32. Further, in the tread pattern of the comparative example, the groove width of the communication lug groove 40 is 21 mm, the groove width of the central main groove 20 is 20 mm, and the groove width of the outermost main groove 20 is 18 mm.

The drainage performance was evaluated by comparing the lap times with the comparative example as "100". The measured lap time [seconds] is indicated by the reciprocal, and the larger the value is, the better the lap time is, and the smaller the value is, the worse the lap time is.

As shown in Tables 1 and 2, the pneumatic tires of Examples 1 to 19 have better lap times and higher drainage performance than Comparative Examples. Further, the pneumatic tires of Examples 1 to 19 have better steering stability performance than Comparative Examples. In particular, when the ratio L2 / TW is in the range of 0.50 or more and 0.60 or less, when the ratio W1 / TW is in the range of 0.1 or more and 0.2 or less, the ratio L1 / TW is 0.15. When the ratio W / TW is within the range of 0.04 or more and 0.10 or less and the repetition pitch length P is within the range of 60 mm or more and 100 mm or less, the center main groove 21 When the phase difference PH is within the range of ± 20 °, when the angle α is within the range of 20 ° or more and 50 ° or less and the angle β is within the range of 50 ° or more and 80 ° or less, the groove width of the center main groove 21 Is wider than the groove width of the first series of lug grooves 41, the groove width of the outermost main groove 22 is wider than the groove width of the center main groove 21, and the groove width of the outermost main groove 22 is the first series. Good results are obtained when the groove width is wider than the groove width of the through lug groove 41, and when the second communicating lug groove 42 has a shape in which the groove width narrows from the tire ground contact end T toward the end in the second land portion 32. It turned out to show.

1 Pneumatic tire 2 Tread rubber 3 Tread part 6 Side wall part 10 Bead part 11 Bead core 12 Bead filler 13 Carcass layer 14 Belt layer 15 Inner liner 16 Side wall rubber 17 Rim cushion rubber 20 Circumferential main groove 21 Center main groove 21E Extension Part 22 Outermost main groove 31 Center land part 32 Second land part 32a Block 33 Shoulder land part 41 First series rug groove 42 Second communication rug groove 51 Center lug groove 141, 142 Cross belt 143 Belt cover CL Tire equatorial line T tire ground contact end

Claims (12)

Two center main grooves extending in the tire circumferential direction and two center main grooves extending in the tire circumferential direction and extending outward in the tire width direction of each of the two center main grooves, which are provided on both the left and right sides in the tire width direction with reference to the tire equatorial line, extend in the tire circumferential direction. A series of lug grooves that communicate with the outermost main groove from the tire ground contact end and are in contact with the center main groove are provided.
The two center main grooves have an amplitude in the tire width direction, and a wavy center land portion is formed on the equator line of the tire by being sandwiched between the two center main grooves.
The groove width of the center main groove changes depending on the position in the tire circumferential direction, and
The groove width of the center main groove is narrower than the other portions at the confluence portion between the center main groove and the first series of lug grooves.
By arranging the first series of lug grooves in the tire circumferential direction, the second land portion formed between the center main groove and the outermost main groove is divided in the tire circumferential direction, and a part of the edge. A pneumatic tire in which an arc-shaped block is formed. When the distance at which the outermost end of the outermost main groove in the tire width direction is separated from the tire equatorial line is L2 and half of the tread deployment width is TW, the ratio L2 / TW is in the range of 0.50 or more and 0.60 or less. The pneumatic tire according to claim 1. According to claim 1 or 2, the groove width of the outermost main groove is wider than the groove width of the center main groove, and the groove width of the outermost main groove is wider than the groove width of the first series lug groove. Pneumatic tires listed. Any one of claims 1 to 3 in which the ratio W1 / TW is in the range of 0.1 or more and 0.2 or less when the groove width of the outermost main groove is W1 and half of the tread development width is TW. Pneumatic tires listed in one. The center main groove is formed in a see-through structure in the tire circumferential direction, and the distance at which the outermost edge of the center main groove in the tire width direction is separated from the tire equatorial line is L1, and half of the tread deployment width is TW. The pneumatic tire according to any one of claims 1 to 4, wherein / TW is in the range of 0.15 or more and 0.25 or less. When the amplitude of the center main groove in the tire width direction is W and half of the tread expansion width is TW, the ratio W / TW is in the range of 0.04 or more and 0.10 or less, and the repeating pitch length of the center main groove. The pneumatic tire according to any one of claims 1 to 5, wherein P is in the range of 60 mm or more and 100 mm or less. The air-filled state according to any one of claims 1 to 6, wherein the two center main grooves are arranged so that the maximum positions of the amplitudes in the tire width direction are displaced from each other within a range of ± 20 °. tire. In the first series of lug grooves, a virtual line connecting the maximum amplitude position inside the center main groove in the tire width direction and the maximum amplitude position outside the center main groove in the tire width direction, and the tire of the center main groove. The angle α formed by the virtual line connecting the maximum amplitude positions on the outer side in the width direction is 20 ° or more and 50 ° or less.
In the lug groove, a virtual line connecting the maximum amplitude position outside the tire width direction of the center main groove and the center position of the width of the first series lug groove in the tire circumferential direction at the tire ground contact end and the tire circumference. The pneumatic tire according to any one of claims 1 to 7, wherein the angle β formed by the virtual line along the direction is 50 ° or more and 80 ° or less. The pneumatic tire according to any one of claims 1 to 8, wherein the groove width of the center main groove is wider than the groove width of the first series of lug grooves. A claim further comprising a second communication lug groove between the first series of lug grooves, which terminates in the middle of the second land portion between the tire ground contact end and the center main groove and the outermost main groove. The pneumatic tire according to any one of 1 to 9. The pneumatic tire according to claim 10 , wherein the second communication lug groove narrows the groove width from the tire ground contact end toward the end in the second land portion. When the distance from the tire equatorial line is L3 and half of the tread deployment width is TW, the ratio L3 / TW is 0.15 or more and 0.20 or less for the terminal position in the second land portion of the second communication lug groove. The pneumatic tire according to claim 10 or 11.

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