Endless belt power transmission systems or components – Friction drive belt
Reexamination Certificate
1999-12-08
2001-09-11
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Friction drive belt
C474S260000
Reexamination Certificate
active
06287230
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an elastomer composition such that the powder resulting from abrasion thereof is prevented from adhering to the counterpart member such as a pulley and to the elastomer surface, and to a power transmission belt comprising said elastomer composition as a component thereof and reduced in abnormal sound emission during running and improved in durability.
PRIOR ART
Power transmission belts are widely used as friction power transmission belts, for example V belts and V rib belts, such as lapped belts and low edge belts, and further as mating power transmission belts, for example timing belts, in the automobile industry and for general industrial purposes. These power transmission belts are generally constituted of an adhesive rubber layer
32
with core wires
31
comprising a polyester or aramide fiber as embedded therein and a compressed rubber layer (bottom rubber layer)
33
layered on said adhesive rubber layer
32
, where necessary together with an upper canvas
34
and/or a lower canvas
35
, respectively adhered to the above assembly, as shown in FIG.
8
.
The elastomer to be used in such power transmission belts is required to have adhesiveness to fibers, resistance to flexing fatigue and like characteristics, in addition to such general characteristics as heat resistance, oil resistance and wear resistance. Among the elastomers so far used widely, natural rubbers, epichlorohydrin rubbers, acrylic rubbers, chloroprene rubbers and the like, in particular, readily form adhesive abrasion dust powders as a result of wear in sliding portions and the phenomenon of such abrasion dust powders sticking to the elastomer surface (hereinafter this phenomenon is referred to as “adhesion wear”) tends to occur. When adhesion wear occurs, the power transmission performance of the power transmission belt is adversely affected and, as a result of abnormal interference with the counter material in sliding portions during running of the belt, abnormal or strange sounds may be emitted and/or other troubles may occur.
The means so far taken to prevent such adhesion wear from occurring comprise (1) increasing the hardness of the elastomer or (2) reducing the coefficient of friction of the elastomer surface, among others. As concrete methods generally employed for realizing the means (1), there may be mentioned, among others, the method comprising increasing the crosslinking density of the elastomer and the method comprising increasing the content of the reinforcing agent, such as carbon black. By such means, the occurrence of adhesion wear can be prevented to some extent. However, the means comprising increasing the hardness has problems; if the hardness is increased to an extent such that the occurrence of adhesion wear can be prevented, the processability of the elastomer may become poor and, if the amount of the reinforcing agent is increased excessively or the crosslinking density is increased excessively, the final product may show so high elastic modulus that the durability of the product under repeated strain and stress may be worsened.
As concrete methods for realizing the means (2), there may be mentioned, among others, the method comprising incorporating a short fiber in the elastomer in an amount sufficient to allow exposure thereof on the elastomer surface, and the method comprising subjecting the elastomer to surface treatment with chlorine, corona, ultraviolet radiation or the like. However, the problem is that these methods readily induce surface cracks.
SUMMARY OF THE INVENTION
In view of such state of the art, the present invention has for its object to provide a power transmission belt which is prevented from occurring the adhesion wear, hence from emitting strange sounds during running, and which is excellent in durability as well as an elastomer composition suited for constituting said belt and showing good processability.
In accordance with a first aspect of the present invention, there is provided a power transmission belt having a bottom rubber layer comprising an elastomer,
wherein the bottom rubber layer satisfies the relation represented by the following formula (1)
X/Y≧
2.5 (1)
in the formula, X is the change in mg in the weight of said layer after 500 wear cycles under a load of 500 grams in Taber's abrasion resistance test with a sand paper (C1500) having a particle size of 10 &mgr;m as the counter material and Y is the area in cm of contact between said counter material and the rubber face of the belt.
In accordance with a second aspect of the present invention, there is provided an elastomer composition wherein the change in the weight of said composition in Taber's abrasion resistance test amounts to 40 mg when the test is carried out under the condition of 500 wear cycles, a load of 500 grams and not greater than 20 &mgr;m of the particle size of the counter material of sand paper.
In accordance with a third aspect of the present invention, there is provided a power transmission belt comprising the above elastomer composition as the constituent material thereof.
REFERENCES:
patent: 4269746 (1981-05-01), Tabar et al.
patent: 4605705 (1986-08-01), Takeshita
patent: 5314140 (1994-05-01), Rotter
patent: 5861212 (1999-01-01), Mori et al.
patent: 0 419 055 A1 (1991-03-01), None
patent: 1 590 802 (1981-06-01), None
Bando Chemical Industries Ltd.
Bucci David A.
Connolly Bove Lodge & Hutz
Johnson Vicky A.
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