Heavy duty pneumatic tire

Patent metadata

Field	Value
Publication number	US-9962997-B2
Application number	US-201515328466-A
Country	US
Kind code	B2
Filing date	Jul 23, 2015
Priority date	Jul 23, 2014
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A pneumatic tire having a tread pattern includes: shoulder lug grooves opening at ground contact edges; center lug grooves having both ends; circumferential primary grooves being formed to wave-like shape and alternately connecting the ends of the center lug grooves and inward ends of the shoulder lug grooves in the tire width direction; center blocks formed in a row defined by the center lug grooves and the pair of circumferential primary grooves; and circumferential secondary grooves being formed in regions of the center blocks and interconnecting center lug grooves adjacent in the tire circumferential direction. The circumferential secondary grooves have secondary groove turning portions, and the center lug grooves have lug groove turning portions and connect to the circumferential secondary grooves at the lug groove turning portions.

First claim

The invention claimed is:

1. A heavy duty pneumatic tire comprising
a tread pattern,
the tread pattern comprising:
a plurality of center lug grooves spaced apart in a tire circumferential direction, the plurality of center lug grooves having two ends and extending in half-tread regions on a first side and a second side in a tire width direction with reference to a tire equator line to cross the tire equator line;
a plurality of shoulder lug grooves spaced apart in the tire circumferential direction, extending outward in the tire width direction in each of the half-tread regions, having ends outward in the tire width direction opening at ground contact edges disposed on either side in the tire width direction, the plurality of shoulder lug grooves being configured so that, in the tire circumferential direction, one shoulder lug groove of the plurality of shoulder lug grooves is provided in between the ends of adjacent center lug grooves, among the center lug grooves, adjacent in the tire circumferential direction;
a pair of circumferential primary grooves disposed in the half-tread regions and formed, in each of the half-tread regions, to extend around an entire circumference of the tire in a wave-like shape with a groove width less than that of the plurality of shoulder lug grooves, in such a way as to alternately connect the ends of the center lug grooves and inward ends of the shoulder lug grooves in the tire width direction;
a plurality of center blocks defined by the plurality of center lug grooves and the pair of circumferential primary grooves and formed in a row in the tire circumferential direction; and
circumferential secondary grooves formed in regions of the center blocks, interconnecting center lug grooves, among the center lug grooves, adjacent in the tire circumferential direction;
each of the center lug grooves having at least one lug groove turning portion with a bent or curved shape,
each of the circumferential secondary grooves having at least one secondary groove turning portion with a bent or curved shape, and connecting to the center lug grooves at the lug groove turning portion,
the at least one secondary groove turning portion being provided with a third groove turning portion and a fourth groove turning portion, linking groove portions linking between either one of the positions of the third groove turning portion and the fourth groove turning portion, and a connecting portion between the circumferential secondary groove and one of the center lug grooves,
an inclination angle of the linking groove portions with respect to the tire circumferential direction being from 0 to 5 degrees, and
a ratio D 3 /LB of a maximum groove depth D 3 of the center lug grooves to a maximum width LB of the center blocks in the tire circumferential direction being from 0.1 to 0.3, a maximum groove depth D 5 of the linking groove portions being shallower compared to the maximum groove depth D 3 of the center lug grooves.

2. The heavy duty pneumatic tire according to claim 1 , wherein the lug groove turning portion includes a first groove turning portion on the first side, the first groove turning portion bending or curving so as to protrude towards a third side in the tire circumferential direction, and a second groove turning portion on the second side, the second groove turning portion bending or curving so as to protrude towards a fourth side that is the opposite side to the third side in the tire circumferential direction,
a first connection end portion on the first side and a second connection end portion on the second side where the center lug grooves each connects to the circumferential primary grooves, connects to the inward ends of the circumferential primary grooves in the tire width direction, and the second connection end portion of each of the center lug grooves is located on the third side in the tire circumferential direction in relation to the first connection end, and
in relation to a center position in the groove width direction of the center lug grooves, an inclination angle, with respect to the tire width direction, of a first straight line connecting between the first connection end and a protruding end at which the first groove turning portion protrudes towards the third side in the tire circumferential direction, and an inclination angle, with respect to the tire width direction, of a second straight line connecting between the second connection end portion and a protruding end at which the second groove turning portion protrudes towards the fourth side in the tire circumferential direction, are greater than an inclination angle, with respect to the tire width direction, of a third straight line connecting between the first connection end portion and the second connection end portion of each of the center lug grooves.

3. The heavy duty pneumatic tire according to claim 2 , wherein, in relation to the center position in the groove width direction of the center lug grooves, a portion of each of the center lug grooves disposed between the first connection end and the protruding end where the first groove turning portion protrudes to the third side in the tire circumferential direction is located on the first straight line or towards the third side in relation to the first straight line, and a portion of each of the center lug grooves disposed between the second connection end and the protruding end where the second groove turning portion protrudes to the fourth side in the tire circumferential direction is located on the second straight line or towards the fourth side in relation to the second straight line.

4. The heavy duty pneumatic tire according to claim 1 , wherein each of the pair of circumferential primary grooves is provided with a raised bottom portion in which the groove depth is partially shallow.

5. The heavy duty pneumatic tire according to claim 4 , wherein a ratio D 2 /T of a groove depth D 2 in the raised bottom portion with respect to a tread width T of a tread portion of the heavy duty pneumatic tire in the tire width direction is less than 0.05.

6. The heavy duty pneumatic tire according to claim 1 , wherein a ratio D 1 /T of a maximum groove depth D 1 of the circumferential primary grooves with respect to the tread width T of a tread portion of the heavy duty pneumatic tire in the tire width direction is from 0.03 to 0.09.

7. The heavy duty pneumatic tire according to claim 1 , wherein a ratio D 5 /D 3 of the maximum groove depth D 5 to the maximum groove depth D 3 is from 0.3 to 0.75.

8. The heavy duty pneumatic tire according to claim 1 , wherein intermediate groove portions that join the positions of the third groove turning portion and the fourth groove turning portion cross the tire equator line.

9. The heavy duty pneumatic tire according to claim 8 , wherein a maximum groove width P 6 of the intermediate groove portions is equal to a maximum groove width P 5 of the linking groove portions, or greater than the maximum groove width P 5 .

10. The heavy duty pneumatic tire according to claim 9 , wherein a ratio P 6 /P 5 of the maximum groove width P 6 to the maximum groove width P 5 is from 1 to 2.5.

11. The heavy duty pneumatic tire according to claim 1 , wherein two start positions in the tire width direction of each of the circumferential secondary grooves extending respectively from the center lug grooves are mutually shifted in position.

12. The heavy duty pneumatic tire according to claim 11 , wherein the two start positions in the tire width direction are located on mutually different sides in the tire width direction, with reference to the tire equator line.

13. The heavy duty pneumatic tire acc

Assignees

• Yokohama Rubber Co Ltd

Inventors

• Yamaguchi Yukihito
• KAKUTA Shoei
• Hamanaka Hideki
• Tauchi Risa
• Sato Toshiyuki

Classifications

• B60C11/11 Primary

  in which the raised area of the pattern consists only of isolated elements, e.g. blocks (B60C11/12, B60C11/13 take precedence) · CPC title

• B60C2011/0346

  with zigzag shape · CPC title

• B60C2011/0348

  Narrow grooves, i.e. having a width of less than 4 mm · CPC title

• B60C2011/0358

  Lateral grooves, i.e. having an angle of 45 to 90 degees to the equatorial plane · CPC title

• B60C2200/065

  for construction vehicles · CPC title