Endless belt power transmission systems or components – Friction drive belt – Including plural interconnected members each having a drive...
Reexamination Certificate
2000-12-08
2004-02-10
Charles, Marcus (Department: 3682)
Endless belt power transmission systems or components
Friction drive belt
Including plural interconnected members each having a drive...
C474S201000, C474S248000, C156S138000
Reexamination Certificate
active
06689004
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a continuously-variable-ratio transmission belt.
BACKGROUND OF THE INVENTION
As is known, continuously-variable-ratio transmissions (CVT) or variable-speed drives employ substantially trapezoidal-section belts, the lateral friction surfaces of which cooperate with respective sides of trapezoidal-grooved pulleys; and the velocity ratio is varied by known mechanisms altering the width of the pulley grooves and hence the winding diameter of the belt.
Low-power transmissions currently employ belts having a body made of elastomeric material and having threadlike longitudinal reinforcing elements for achieving the required tensile strength. The body of elastomeric material normally has inner and outer notches to make the belt fairly flexible and enable the belt to operate with small winding diameters while maintaining a sufficiently extensive lateral surface.
Higher-power transmissions employ belts having transverse stiffening elements, which are superimposed on respective teeth of the inner and outer notches to prevent transverse buckling of the belt. The stiffening elements superimposed on each pair of opposite inner and outer teeth may be connected by a connecting element through the body of the belt.
Belts of the above type, in which power is transmitted by direct contact between the elastomeric material of the body and the pulleys, are unsuitable for high-power transmissions, such as those used in automobile variable-speed drives.
These normally employ metal belts, which, however, besides being relatively expensive and heavy, are exclusively oil-bath operated and therefore of limited application.
In an attempt to overcome the limitations of metal belts, dry transmission belts have been proposed comprising a continuity element in the form of an endless belt with an elastomeric body and a number of substantially inextensible longitudinal inserts; and a number of separate friction elements or blocks made of plastic material, carried by the continuity element, and defining the lateral friction surfaces cooperating with the pulleys. The friction blocks are normally fitted to the longitudinal continuity element by means of auxiliary connecting elements or by force-fitting the blocks onto the continuity element. Belts of the type briefly described above are complex and expensive, and involve a good deal of painstaking assembly work.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a high-power CVT belt suitable, for example, for automobile variable-speed drives, and which provides for eliminating the aforementioned drawbacks typically associated with known belts.
According to the present invention, there is provided a continuously-variable-ratio transmission belt comprising a beltlike continuity element having a body of elastomeric material and a number of threadlike longitudinal inserts; and a number of separate friction blocks made of plastic material, fixed to said continuity element, and each defined by two lateral surfaces converging inwards of said belt and cooperating with respective sides of a groove of a trapezoidal-grooved pulley; characterized in that said continuity element comprises inner teeth defined by a number of first teeth alternating with respective cavities, and outer teeth defined by a number of second teeth alternating with respective cavities; and in that each of said friction blocks incorporates at least one of said first teeth and at least one of said second teeth.
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Celio Luigi
Lolli Sergio
Charles Marcus
Dayco Europe S.r.l.
Nissim, Esq Stuart H.
Synnestvedt, Lechner & Woodbridge
Woodbridge Richard C.
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