Endless belt power transmission systems or components – Positive drive belt
Patent
1998-12-07
2000-07-11
Bucci, David A.
Endless belt power transmission systems or components
Positive drive belt
474204, 474260, 474268, F16G 100
Patent
active
060865008
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a toothed belt, and more particularly relates to an improvement of the foundation fabric of a toothed belt to whose engaging surfaces a foundation fabric is adhesive-bonded.
The present invention further relates to an improved woven fabric used as foundation fabric of a toothed belt.
BACKGROUND OF THE INVENTION
Toothed belts to whose engaging surfaces a foundation fabric is adhesive-bonded for the purpose of protecting the surface are known from JP, U 62-204059 (U.S. Pat. No. 4,826,472; EP-B1 0 271 587) and other publications; however, in the foundation fabric thereof crimped yarns of synthetic fibers are used as weft yarns extending in the longitudinal direction of the toothed belt. These toothed belts are formed, as shown in FIG. 2, by locating a foundation fabric 2, tensil cords 3 and unvulcanized rubber 4 on a mold 1 having protrusions and recesses on its surface and by vulcanizing the unvulcanized rubber 4 by applying heat and pressure thereto; and, as shown in FIG. 3, the belt teeth 6 are formed on the engaging surface along the recesses of the mold 1. I.e., a requirement of said foundation fabric 2 is that it must be capable of being elongated during its formation by being subjected to low loads by as much as some ten percent from a predominantly flat condition to a condition in which it follows the protrusions and recesses of the mold 1. Accordingly, crimped yarns of synthetic fibers are used in this woven fabric 2 as weft yarns extending in the longitudinal direction of the toothed belt, so that the woven fabric can be easily elongated by stretching the crimps.
The foundation fabric of conventional toothed belts is woven in a 2/2 double-faced twill pattern, and false-twisted yarns of different false twist directions are combined in parallel and used as weft yarn so that the exposure condition of the yarns on both faces is equal.
Toothed belts require adequate durability because, being operated at high speeds while rotating on pulleys, repeated bending creates forces which may tear the foundation fabric off the engaging surface of the belt; there are even cases in which the foundation fabric has actually been torn off due to long use. Further, when the toothed belt is in operation, a momentum is transmitted by the engagement of the tooth profile of the toothed belt with the tooth profile of the pulleys; therefore, sounds are produced by the collision of the tooth surfaces when the tooth profiles engage, the friction between the tooth surfaces during rotation, the friction occurring when the toothed belt separates from the pulley, etc.; moreover, currents of air occur rapidly when the tooth profiles engage and disengage, producing a disagreeable noise.
These problems have hardly been addressed in the conventional toothed belts described above, which, lacking in durability, do not endure long periods of use, and which produce a fairly loud noise during operation.
SUMMARY OF THE INVENTION
Having reflected on the above circumstances, it is the object of the present invention to provide a toothed belt which, compared to conventional toothed belts, has improved durability and produces less noise during operation.
The inventors of the present invention, while making diligent studies to achieve this object, accomplished the present invention by discovering that the above-mentioned problems can all be solved at the same time by using a woven fabric, woven with weft yarns comprising a plurality of false-twisted yarns that are false-twisted in the same false twist direction as weft yarns, as foundation fabric of a toothed belt. Because the weft yarns of the fabric are false-twisted in the same direction, the exposure of these yarns is not the same on both sides of the fabric. That is, one side of the fabric will exhibit a greater exposure of these yarns than the other side.
I.e., the present invention relates to a toothed belt having a foundation fabric adhesive-bonded along the engaging surface thereof, wherein the yarns of said foundation fabric
REFERENCES:
patent: 4219996 (1980-09-01), Edgawa et al.
patent: 4826472 (1989-05-01), Sato
patent: 5346731 (1994-09-01), Nakanishi
patent: 5382200 (1995-01-01), Kimoto
patent: 5406782 (1995-04-01), Inuyama et al.
patent: 5876297 (1999-03-01), Takeuchi
Isshiki Shigehiro
Kida Hiroshi
Matsuki Atsushi
Yamada Mitsuho
Ashimori Industry Co. Ltd.
Bucci David A.
Charles Marcus
Unitta Co., Ltd.
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