Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1998-03-12
2001-04-10
Maki, Steve D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209280
Reexamination Certificate
active
06213180
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a pneumatic radial tire, and more particularly to a pneumatic radial tire for passenger car having high running-performances and provided with a directional tread pattern specifying a rotating direction of the tire when mounted onto a vehicle. Many blocks are formed in the trend pattern at given intervals in a circumferential direction of the tire by a plurality of circumferential grooves arranged at given intervals in an axial direction of the tire and extending in parallel to or substantially in parallel to the circumferential direction. A plurality of directional slant grooves arranged in the trend pattern at given intervals in the circumferential direction and obliquely extending with respect to the circumferential direction.
The term “directional slant groove” used herein means a groove obliquely extending with respect to the circumferential direction and specifying a rotating direction (forward direction) of the tire to precedently contact a portion of the slant groove near to an equatorial plane of the tire with the ground and succeedingly contact a portion of the slant groove apart from the equatorial plane with ground when the tire is mounted onto a vehicle or forming so-called directional tread pattern.
2. Description of Related Art
In the high running-performance pneumatic radial tire for a passenger car, it is required to have excellent steering stability on a dry road surface and a low level of tire noise while highly maintaining a drainage property on a wet road surface. However, these performances required in the tire conflict with each other in the pattern design, so that it is very difficult to provide a tire simultaneously establishing excellent drainage property in the running on wet road surface, steering stability in the running on dry road surface and low tire noise level according to the conventional technique.
In order to enhance the drainage property in the running on wet road surface, for instance, there is proposed and practiced a tread pattern wherein many blocks are formed at intervals in an axial direction and a circumferential direction of the tire by a plurality of circumferential grooves straightforward extending in the circumferential direction and a plurality of slant grooves obliquely extending with respect to the circumferential direction. In order to more improve the drainage property in the running on wet road surface, it is favorable to render the slant groove into a steeply slant groove extending at a small inclination angle with respect to the circumferential direction. On the other hand, in order to enhance the steering stability in the running on dry road surface, it is favorable to render the slant groove into a gently slant groove extending at a large inclination angle with respect to the circumferential direction. Particularly, when the inclination angle of the slant groove is made large with respect to the circumferential direction, there is caused a problem of deteriorating the tire noise level.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to solve the aforementioned problems of the conventional technique and to provide a high running-performance pneumatic radial tire for a passenger car having an excellent steering stability on a dry road surface and a low level of tire noise while highly maintaining a drainage property on wet road surface.
According to the invention, there is the provision of in a pneumatic radial tire for passenger car comprising many blocks formed at intervals in circumferential and axial directions of the tire by a plurality of circumferential grooves arranged at intervals in the axial direction and extending in parallel to or substantially in parallel to the circumferential direction and a plurality of directional slant grooves arranged at intervals in the circumferential direction and obliquely extending with respect to the circumferential direction, and provided with a directional tread pattern specifying a rotating direction of the tire when being mounted onto a vehicle to precedently contact a portion of the directional slant groove near to an equatorial plane of the tire with ground and succeedingly contact a portion of the directional slant groove apart from the equatorial plane with ground, the improvement wherein:
(1) at least a part of said directional slant grooves branches from a circumferential groove arranged in the vicinity of a center of the tread pattern among said circumferential grooves and extends toward and is opened at an end of a ground contact region of the tread;
(2) at least a part of corner portions of each of said blocks forms an acute angle of 10-60° defined by said circumferential groove and said directional slant groove; and
(3) a surface of said corner portion of the block having an acute angle of 10-60° is beveled over a distance of 10-30 mm from a tapered end thereof in a longitudinal direction so as to gradually shallow from the tapered end toward a width widened portion of the block in both stepping-in and kicking-out sides of the block.
In a preferable embodiment of the invention, the angle of the corner portion located toward the center of the tread pattern in the block defined by the circumferential groove and the directional slant groove is smaller than the angle of the corner portion located toward the tread end.
In another preferable embodiment of the invention, a side facing the equatorial plane in two sides of the corner portion of the block formed in the vicinity of the center of the tread pattern extends at an angle of 0-20° with respect to the circumferential direction of the tire.
In the other preferable embodiment of the invention, a width of the directional slant groove adjacent to the corner portion having an acute angle of 10-60° at a stepping-in side of the block is narrower than a width of the directional slant groove adjacent to the corner portion having an acute angle of 10-60° at a kicking-out side of the block.
REFERENCES:
patent: 4057089 (1977-11-01), Johannsen
patent: 4690189 (1987-09-01), Bradisse et al.
patent: 4832099 (1989-05-01), Matsumoto
patent: 5109903 (1992-05-01), Watanabe et al.
patent: 5234042 (1993-08-01), Kuhr et al.
patent: 5291929 (1994-03-01), Daisho et al.
patent: 5375639 (1994-12-01), Suzuki et al.
patent: 5421391 (1995-06-01), Himuro
patent: 5423364 (1995-06-01), Himuro
patent: 5707461 (1998-01-01), Himuro
patent: 5714021 (1998-02-01), Ochi
patent: 5746849 (1998-05-01), Hutson et al.
patent: 5885384 (1999-03-01), Himuro
patent: 90 02 986 (1991-05-01), None
patent: 0 064 934 A2 (1982-11-01), None
patent: 0 233 135 A2 (1987-08-01), None
patent: 627332 (1994-12-01), None
patent: 0 678 403 A1 (1995-10-01), None
patent: 688685 (1995-12-01), None
patent: 0 705 718 A2 (1996-04-01), None
patent: 705718 (1996-04-01), None
patent: 0 713 789 A1 (1996-05-01), None
patent: 753418 (1997-01-01), None
patent: 0 812 709 A1 (1997-12-01), None
patent: 1549347 (1979-08-01), None
patent: 63-312204 (1988-12-01), None
patent: 2-006204 (1990-01-01), None
patent: 5-319025 (1993-12-01), None
patent: 7-149114 (1995-06-01), None
patent: 9-2025 (1997-01-01), None
Abstract for Japan 5-319025.
Bridgestone Corporation
Maki Steve D.
Sughrue Mion Zinn Macpeak & Seas, PLLC
LandOfFree
Pneumatic radial tire including beveled acute angle corner... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Pneumatic radial tire including beveled acute angle corner..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pneumatic radial tire including beveled acute angle corner... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2463380