Resilient tires and wheels – Tires – resilient – Anti-skid devices
Reexamination Certificate
1998-12-07
2001-01-23
Maki, Steven D. (Department: 1733)
Resilient tires and wheels
Tires, resilient
Anti-skid devices
C152S209260, C152S902000, C152SDIG001
Reexamination Certificate
active
06176284
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire having projections standing out from the bottom of the grooves in the tire tread to prevent stones from being trapped therein.
In vehicles which travel on dirt roads such as trucks, construction vehicles and the like, small foreign objects such as stones, pebbles and the like are liable to be trapped in the tread grooves on the tires of the vehicles.
While traveling, the trapped stones are repeatedly pressed against the groove walls and groove bottom. As a result, the groove bottom and the structure inside the tire (such as reinforcing cord layers) are often seriously damaged. Therefore, not only the durability of the tread portion but also the retread rate of the used tires decreases.
In order to avoid stone trapping, many ideas have been proposed. For example, in laid-open Japanese patent application Nos. JP-A-60-189608 and JP-A-61-291203, a tire having a rib type tread pattern is disclosed, wherein a circumferentially and continuously extending zigzag groove is provided therein with circumferentially discontinuous projections. In U.S. Pat. No. 5160385, a tire having a block type tread pattern is disclosed, wherein circumferentially continuously extending grooves are provided therein with circumferentially discontinuous projections. The circumferential grooves are interconnected by axial grooves, and some of the projections disposed at the junctions of the circumferential grooves and axial grooves have branches which extend into the axial grooves but immediately end.
In general, stone trapping is liable to occur in a central tread region where the ground pressure is relatively high. If a block pattern tire is made according to the above-mentioned assumption, then in center tread region, stones are still liable to be trapped in the circumferential groove between the projections and also in the axial grooves. Thus, the tire may be damaged.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a pneumatic tire having a block type tread pattern in which stone trapping, especially in central tread region, is effectively decreased so as to prevent the tread rubber and reinforcing cord layers from being damaged and to thereby improve the tread durability and increase the retread rate.
According to one aspect of the present invention, a pneumatic tire comprises
a tread portion with a block tread pattern,
the tread portion being provided with a mesh of grooves to define a plurality of blocks consisting of shoulder blocks adjacent to tread edges and central blocks other than the shoulder blocks,
each central block being surrounded by at least one projection,
the at least one projection being disposed in the mesh of grooves and projecting from a bottom of the grooves and being spaced from the groove walls,
each projection comprising a continuous series of alternating main portions and coupler portions, the main portions being relatively wider than the coupler portions,
a height H1 of the main portions being in the range of from 10 to 25% of a depth GH of one of the grooves, a height H2 of the coupler portions being in the range of from 5 to 10% of the groove depth GH, a length L1 of each of the main portions being in the range of from 3 mm to 10 mm, a length L2 of each of the coupler portions being in the range of from 2 mm to 8 mm, and a width W2 of the coupler portions being in the range of from 0.5 mm to 2 mm, the main portions comprises first main portions and second main portions, the first main portions being disposed between junctions of the grooves and being relatively taller than the second main portions.
Preferably, the groove walls comprise a perpendicular under part of which width is substantially constant and a slanting upper part of which width increases from the lower end to the upper end thereof. The boundary between the upper and under parts is at a height KH of from 15 to 30% of the groove depth GH.
REFERENCES:
patent: 2604920 (1952-07-01), Kirby
patent: 4345632 (1982-08-01), Takigawa et al.
patent: 4945966 (1990-08-01), Ogawa
patent: 5024260 (1991-06-01), Ochiai
patent: 5160385 (1992-11-01), Goto et al.
patent: 5180453 (1993-01-01), Fukasawa et al.
patent: 5361815 (1994-11-01), Loser et al.
patent: 5417269 (1995-05-01), Kinoshita et al.
patent: 5975172 (1999-11-01), Nakatsuji
patent: 6000451 (1999-12-01), Takada
patent: 3727050 (1989-02-01), None
patent: 63-297108 (1988-12-01), None
patent: 2-254004 (1990-10-01), None
patent: 3-132403 (1991-06-01), None
patent: 5-278414 (1993-10-01), None
patent: 6-99705 (1994-04-01), None
Abstracts for Japan 11-180112.
Birch & Stewart Kolasch & Birch, LLP
Maki Steven D.
Sumitomo Rubber Industries Ltd.
LandOfFree
Pneumatic tire 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 tire, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Pneumatic tire will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2536317