Title of Invention

ENDLESS POWER TRANSMISSION BELT

Abstract

An endless power transmission belt comprising an inner compression section, an outer tension section, and a load-carrying section disposed between said compression and tension sections and having longitudinally extending load-carrying cords such as of aramid; the improvement, wherein said load-carrying cords are made of a high modulus material and said belt comprises a polymeric backing layer such as of ethylene propylene diene monomer disposed outwardly of said tension section and forming the outer surface of said belt, and a fabric layer disposed between said backing layer and said load-carrying cords, for example adjacent to said backing layer.

Full Text

Technical Field This invention relates to an endless power transmission bell, also known as a V-belt. Such belts are widely used for automoli^ye or industrial purposes and are primarily comprised of an outer compression section, an inner tension section, and a toad-carrying section disposed between the compression and tension sections. The ioad-carrying section utilizes longitudinally extending load-carrying cords imbedded in a cushion of polymeric material. For special purposes, such belts may also include other layers of material. Such belts may have a simple trapezoidal cross-section, or may be of the multi-rib type comprising a plurality of laterally spaced trapezoidal sections formed in the compression section. Background Art The load-carrying cords utilized in the belts have evolved through the years from natural materials to rayon, nylon, or similar synthetic materials, to materials having a high modulus, such as aramid. These later materials are needed to create belts which are stronger, more stretch resistant, provide longer running times without losing their properties. Unfortunately, the elevated temperatures required to cure such belts cause significant expansion of the curing molds and the cords will tend to float in a random pattern unless some control is provided. This has been done in the past by forming a barrier of fabric or lateral cords (also known as tire cords). It has been found that the use of a single composite layer of fabric with a heavy rubber coating as a barrier results in an excessive splice thickness which will damage the cord when the bell is flexed. Typical of prior art constructions are shown in Waugh 3.478,613: Meadows 3,863,515; and Wolfe 4,022,070. Disclosure of the Invention In order to control the Iccation of the aramid load-carrying cords, it has been found that this can be accomplished by providing a fabric layer on the tension section outvyardly of the load-carrying section. A second, discrete, rubber backing layer is disposed outwardly of the fabric layer to provide a pulley engaging surface. Despite the fact that this adds to the thickness of the cross-section of the belt, it succeeds in its purpose of preventing abrasion between the outer surface of the belt and the pulley. The result of the improvement is a belt having a greater belt life and a reduction in backside pulley wear, particularly in dusty environments such as in agricultural machinery. In addition, the backside coefficient of friction is greater than if fabric backing layers were to be used, and thus becomes important v/here the outer surface of the belt, which is the backing layer, engages a back side idler pulley in certain power transmission systems. The backing layer works in conjunction with an additional fabric layer, preferably rubber-impregnated, which is disposed between the backing layer and the load-carrying cords. A further advantage of this construction is the reduction in thickness of the splice, hereinafter sometimes referred to as splice thickness or simply splice, which is required in the fabric layer. In most constructions, the splice forces the strength cord to be misaligned in an axial direction, which is obviously undesirable. The combination of the fabric layer and the backing layer reduces the splice thickness to avoid the misalignment. The novel design is particularly useful in multiple rib belts, of the type shown in U.S. Patent No. 4,139,406, issued to Richmond et al. It should be noted that backing layers have been used in other belt structures, such as designated by reference number 15 in U.S. Patent No. 4,617,075 issued to Wetzel et al.; such layers were not intended for the purposes outlined above, but were used in the process for forming a toothed "timing" belt. This patent also shows a layer 15A which is not fabric, but only a fiber reinforced rubber layer. Thus, the present structural arrangement creates unexpected results for creating a useful product. Brief Description of the Drawings The features of the invention, and its technical advantages, can be seen from the following description of the preferred embodiments together with the claims and the accompanying drawings, in which: FIG. 1 is a perspective view with parts in cross-section, parts in elevation, and parts broken away illustrating one exemplary embodiment of the belt body of the invention, and FIGS. 2-4 are partial views, similar to FIG. 1, illustrating various types of alternative fabric arrangements. Detailed Description of Preferred Embodiments As shown in FIG. 1, the endless power transmission belt 11 is shown as a portion of an entire continuous belt adapted to be operated between driving and driven pulleys in an endless manner well known in the art. The belt has a compression section 12, defined by a plurality of longitudinally extending ribs 13, each having a trapezoidal cross-section (also referred to as truncated vee ribs) extending partially into the compression section, having inner surfaces 14 and angled side surfaces 15. The compression section is composed of a rubber material well-known in the art. A tension section 16, composed of a similar material, is disposed outwardly of the compression section. A load-carrying section 17 is disposed between the compression and tension sections, and is composed of a rubber material well-known in the art. This section also comprises a plurality of longitudinally extending cords or cord windings 18 made of high modulus material, the preferred materia! being aramid. These cords are imbedded in the section 17 and are utilized as load-carn/ing cords, and as indicated above, they are stretch-resistant and provide additional improved belt characteristics. In order to prevent the cords from floating during construction, a backing layer and a fabric layer are formed as part of the belt- The backing layer 19 is disposed outwardly of the tension section and also forms the outer surface 20 of the belt. This surface 20 also has the additional function of acting as a wear surface against a back side idler which is used in some belt drive systems, and provides a higher coefficient of friction than a fabric backing which is frequently used. The backing layer has a thickness ranging from .038 to .127cm (.015 to .050 inch), and is composed of a special polymeric material such as EPDM (ethylene propylene diene monomer). The fabric layer 21 is disposed in the tension section, preferably adjacent the backing layer and the \oa6 than in conventional constructions. As sliown in FIG. 1, this avoids misalignment of the strength cords 18. The splice 24 preferably has a maximum thickness of .178cm (.070 inch). As alternative forms of the invention, it is contemplated to use other types of fabric instead of the square woven material of layer 21. FIG. 2 illustrates a belt 31 having a construction similar to belt 11, except that the fabric layer 32 is form.ed of a knitted material similar to that shown in the Richmond patent. As in FIG. 1, the fabric layer is formed with ends 33 and 34 which have a splice 35 similar to splice 24, FIG. 3 illustrates belt 41 similar to belts 11 and 31, except that the fabric layer 42 is formed of a structure known as "tire cord'\ consisting of transversely extending strength cords and weak tie strands which hold the strength cords in a substantially parallel relationship. This type of cord is also shown in the Richmond patent. The fabric layer is also formed with ends 43 and 44 overlapped to form splice 45 similar to the splices 24 and 35. FIG. 4 illustrates a belt 51 similar in construction to the other belts, except that the fabric layer 52 is formed of a bias laid woven fabric referred to as "stress-relieved", in which the warp and weft threads are disposed at an angle of 95° to 155° to each other. Such a fabric is shown in the above-referenced Waugh patent. The fabric layer is also formed as a sheet having ends 53 and 54 which are overlapped to form splice 55, similar to the other splices. Reference has been made throughout this application to splice thickness. What is meant by splice thickness is the total thickness of the spliced structure at the location of the splice. The invention described herein comprises a belt structure and method in which the "fabric layer" and the "backing layer" comprise separate and distinct layers, and further are installed in the belt discretely during the building process. This is distinct from a structure and method in which the "backing layer" is laminated to the "fabric layer" in a separate operation and the resulting composite is then applied to the belt during the building process. This is the primary distinction which ensures that the splice thickness can be minimized— the splice in the "backing layer" can be staggered some distance away from the splice in the "fabric .layer", in which case the maximum splice thickness will be limited to twice the fabric thickness or twice the backing thickness (whichever is thicker), rather than twice the combined thickness of a composite containing both elements. (This maximum in either case is reached with a plain lap splice; a butt splice or bevel splice—with or without sewing—would have a thickness substantially equal to the structure spliced, whether "backing", "fabric", or "composite". A skived tap splice, in which the rubber "backing" is removed from the ends to be overlapped in the splice, would have a maximum thickness equal to two fabric layers.). Other modifications are also contemplated. For example, instead of the trapezoidal or truncated vee ribs, fully V-shaped ribs may be utilized, as shown for example in FIG. 5 of the above-referenced Richmond patent. Other modifications are also contemplated as being within the scope of the inventive concept. The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims. WE CLAIM: 1. An endless power transmission belt comprising an inner compression section (12), an outer tension section (16), and a load-carrying section (17) disposed between said compression and tension sections and having longitudinally extending load-carrying cords (18) such as of aramid; the improvement, wherein said load-carrying cords (18) are made of a high modulus material and said beU (11, 31, 41, 51) comprises a polymeric backing layer (19) such as of ethylene propylene diene monomer disposed outwardly of said tension section (16) and forming the outer surface (20) of said belt, and a fabric layer (21, 32, 42, 52) disposed between said backing layer (19) and said load-carrying cords (18), for example adjacent to said backing layer (19). 2. The belt as claimed in claim 1, wherein said belt (11, 31, 41, 51) is comprised of a plurality of longitudinally extending ribs (13) in said compression section (12), wherein said ribs (13) preferably have a trapezoidal cross-section. 3. The belt as claimed in claim 1, wherein said backing layer (19) has a thickness between 0.038 and 0.127 cm, and said fabric layer (21, 32, 42, 52) has a thickness between 0.013 and 0.089cm. 4. The belt as claimed in claim 1, wherein said fabric layer (21, 32, 42, 52) comprises a rubber impregnated fabric, which may be selected from a group consisting of knitted, square woven, tire cord, or stress-relieved fabrics. 5. The belt as claimed in claim 1, wherein said fabric layer (21, 32, 42, 52) comprises transversely extending ends (22, 23; 33, 34; 43, 44; 53, 54) joined together by a splice (24, 35, 45, 55), said splice having a maximum thickness of 0.178cm. 6. A method of making an endless power transmission belt having an inner compression section (12), an outer tension section (16), and a load-carrying section (17) disposed between said compression and tension sections and having longitudinally extending load-carrying cords (13) such as of aramid; the improved steps characterized by forming said load-carrying cords (18) of high modulus material, disposing a polymeric backing layer (19) such as of ethylene propylene diene monomer outwardly of said tension section (16) and forming the outer surface (20) of said belt, and disposing a fabric layer (21, 32, 42, 52) between said backing layer (19) and said load-carrying cords (18). 7. The method as claimed in claim 6, wherein the step of forming said backing layer (19) to have a thickness between 0.038 and 0.127cm, and forming said fabric layer (21, 32, 42, 52) to have a thickness between 0.013 and 0.089cm, 8. The method as claimed in claim 6, wherein the step of disposing said backing layer (19) adjacent said fabric layer (21, 32, 42, 52). 9. The method as claimed in claim 6, wherein the step of forming said fabric layer (21, 32, 42, 52) of a rubber impregnated fabric, which may be selected from a group consisting of knitted, square-woven, tire cord, or stress-relieved fabrics. 10. The method as claimed in claim 6, wherein the step of forming said fabric layer (21, 32, 42, 52) with two ends (22, 23; 33, 25 34; 43, 44; 53, 54) and splicing said ends together to form a splice (24, 35, 45, 55) having a depth of not more than 0.178cm.

Documents:

1087-chenp-2003 abstract duplicate.pdf

1087-chenp-2003 claims duplicate.pdf

1087-chenp-2003 description (complete) duplicate.pdf

1087-chenp-2003 drawings duplicate.pdf

1087-chenp-2003-abstract.pdf

1087-chenp-2003-assignement.pdf

1087-chenp-2003-claims.pdf

1087-chenp-2003-correspondnece-others.pdf

1087-chenp-2003-correspondnece-po.pdf

1087-chenp-2003-description(complete).pdf

1087-chenp-2003-drawings.pdf

1087-chenp-2003-form 1.pdf

1087-chenp-2003-form 26.pdf

1087-chenp-2003-form 3.pdf

1087-chenp-2003-form 5.pdf

1087-chenp-2003-other documents.pdf

1087-chenp-2003-pct.pdf