POWER TRANSMISSION BELT

Abstract: A multiple rib power transmission belt (13) arranged for low noise operation is disclosed. The ribs (15) of the belt (13) are provided with buried fabric layers (21) ad­ jacent the distal portion (20) of the compression section of the ribs. The fabric layers (21) are exposed at the raw edge sides of the ribs. Short transversely extending fibres (24) may be included in the rib elements (15) which are also exposed at the raw edge sides of the ribs. Tensile cords (17) of the belt may alternatively be disposed within the ribs (15) or in the tie band portion (14) of the belt (13), as desired. The grooves (16) between the ribs (15) extend to the tie band portion (14). In one form, the distal portion (20) of the ribs (15) is provided with transversely extending grooves so as to define a cog belt construction wherein the buried fabric follows the cog configuration. The arrangement described permits low noise operation.

Description: POWER :TRANSMISSION -BELT This invention relates to power transmission belts- and in particular to multiple rib power transmission belts. In one form of multiple rib power transmission belt, a plurality of ribs are maintained in parallel, side-by-side spaced relationship by an outer band to which the ribs are joined. One example of such a banded belt construction is illustrated in U.S. Letters Patent 3,948,113 of Delyn M. Stork. Another example of such a belt construction is illustrated in U.S. Letters Patent 4,177,688 of Anderson W. Howerton et al. In each of these patents, the V-belt portions define distal compression sections which are free of covering fabric. In another form of such a banded belt construction, the ribs are covered with a fabric. Such a construction is illustrated in U.S. Letters Patent 3,523,461 of Paul E. Nemecek et al. Similar covered rib banded belts are illustrated in U:S. Letters Patent 3,564,933 of Donald E. Clinkenbeard, 3,853,017 of JackD. White et al, 3,996,813 of Dewey D. Henderson et al, and 4,011,766 of Dale L. Waugh. It has been found that such banded belt structures have a serious problem in the amount of noise developed in the use of the belt. More specifically, it has been found that noise is produced when the rib is pulled out of the pulley. The present invention comprehends an improved multiple rib banded power transmission belt arranged to have reduced noise in the operation thereof. More specifically, the invention comprehends the provision of such a power transmission belt wherein at least one layer of transversely extending reinforcing fabric is buried within the innermost compression portion of each rib so as to have the side edges thereof exposed at the raw edge rib sides. The invention further comprehends the provision of such a belt wherein short transversely extending reinforcing fibers are provided in the compression portion of the ribs outwardly of the reinforcing fabric. Still further, the invention comprehends the provision of such a power transmission belt wherein the tensile cords are disposed within a tensile body portion of the belt in the outer portion of the belt, with the grooves between the ribs extending outwardly from the innermost portion to inwardly adjacent the tensile body portion. The invention further comprehends the provision of such a power transmission belt wherein the tensile body portion is provided in the ribs adjacent the outer portion of the belts with the grooves between the ribs extending outwardly from the innermost portion to the outer portion of the belt. Still further, the invention comprehends the provision of such a power transmission belt wherein the innermost compression portion of each rib defines a plurality of longitudinally spaced, transversely extending, downwardly opening grooves. The invention further comprehends the provision of such a power transmission belt wherein the buried fabric comprises a canvas fabric. Still further, the invention comprehends the provision of such a power transmission belt wherein the buried fabric has preselected characteristics for improved noise reduction. In the illustrated embodiment, the buried fabric layer may include a layer of rubber laminated to the fabric. Thus, the power transmission belt construction of the present invention is extremely simple and economical of construction, while yet providing the highly desirable low-noise operation characteristics discussed above. Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein: FIGURE 1 is a perspective view of a power transmission system having a power transmission belt embodying the invention; FIGURE 2 is a fragmentary sectional perspective view of a power transmission belt embodying the nvention; FIGURE 3 is a fragmentary sectional view of a modified form of power transmission belt embodying the invention; and FIGURE 4 is a fragmentary sectional perpsective view of still another modified form of power transmission belt embodying the invention. In the exemplary embodiment of the invention as disclosed in the drawing, a power transmission belt generally designated 10 embodying the invention is shown for use in transmitting power between a pair of multiple grooved pulleys 11 and 12. The invention comprehends the construction of the power transmission belt so as to have effectively minimized noise in the power transmission operation thereof, such as resulting from the movement of the belt outwardly from the pulley as the belt passes therefrom. The invention comprehends the provision of the belt as a multiple rib banded belt, such as belt con struction 13 illustrated in Figure 2 of the drawing. Thus, as shown therein, the banded belt includes an outer band portion 14 to which are joined a plurality of ribs 15 separated from each other by grooves 16 and extending in parallel relationship longitudinally of the continuous extent of the belt illustrated in Figure 1. As seen in Figure 2, each rib is of trapezoidal cross section. In the embodiment of Figure 2, a plurality of tensile cords 17 are provided in the band portion 14 of the belt outwardly of the ribs. The tensile cords are formed of high strength material so as to limit the longitudinal extensibility of the belt in use. As further shown in Figure 2, the band portion 14 may be provided with an outer fabric cover 18. Grooves 16 extend to the tensile body portion 19 of band 14 in which the tensile cords 17 are disposed. Thus, in the embodiment of Figure 2, the ribs define the compression portion of the belt, having an innermost portion 20 defining the distal portion of each rib. Buried in each of the distal portions 20 of the ribs is at least one layer of reinforcing fabric 21 extending transversely across the rib. In the embodiment of Figure 2, two such fabric layers are illustrated. As shown, each of the ribs is a raw edge rib, i.e., having no covering fabric thereon. Thus, each of the fabric layers 21 is exposed at the raw edge, such as raw edge 22 illustrated in Figure 2. In the illustrated embodiment, each of the fabric layers 21 is formed of a laminate of rubber and fabric. Each rib defines a compression portion of the belt with the portion 20 thereof defining the distal innermost portion of the compression portion. Outwardly of the fabric layers 21, the compression portion is provided with a plurality of distributed short, transversely extending reinforcing fibers 24 which, as indicated in Figure 2, are exposed in the raw edge surface 22. Tensile body 19 is defined by an upper binding rubber layer 25 and a lower binding rubber layer 26 formed of similar material, such as natural rubber, styrene butadiene rubber, chloroprene rubber, butadiene rubber, or blends thereof. The tensile cords 17, as indicated above, are formed of high strength having low elongation, and illustratively, may be formed of polyester synthetic resin, nylon, aromatic polyamides such as KEVLAR , and the like. Cover fabric 18 may comprise a rubber-coated fabric canvas made of cotton yarn or blended yarn of cotton and suitable synthetic resin fibers. As shown, the cover fabric may be bias cut and may have a crossing angle between the warp and woof fibers in the range of approximately 950 to 1500. Thus, the cover fabric forms a tension portion of the belt outwardly of the tensile cords 17. The compression portion 23 defined by the ribs may be formed of a rubber similar to that of the tensile body. The reinforcing fabric 21 may comprise a rubbercoated canvas fabric which may be formed of cotton yarn or yarn blended of cotton yarn and suitable synthetic resin fibers. The reinforcing fabric 21 may be bias cut similar to cover fabric 18 and may have warp and woof yarns with a crossing angle in the range of approximately 950 to 1500. The reinforcing fabric yarns may comprise cotton yarns or blended yarns of cotton yarns and suitable synthetic resin fibers, both in the warp and woof. Alternatively, the reinforcing fabric may consist of wooly-processed crimped nylon in the warp and cotton yarn or nylon yarn in the woof. The belt construction 13 has unexpectedly been found to run extremely silently in transmitting power, such as between pulleys 11 and 12 illustrated in Figure 1. Referring now to the embodiment of Figure 3, a belt generally designated 113 is shown to comprise a belt generally similar to belt 13 but having grooves 116 which extend through the tensile body 119 to the band 114. The lowermost fabric layer 118 of the tension portion of the belt defined by band 114 defines the outermost extension of the grooves 116 and serves to connect the ribs 115 in accurately maintained similar extension. More specifically, the pitch line of the tensile cords 117 being disposed within the ribs provides improved power transmission by the ribs as a result of their wedged engagement in the grooves of the pulleys. Another embodiment of the invention is illustrated in Figure 4 to comprise a power transmission belt generally designated 213 which is similar to belt 113, but wherein the distal portions 120 of the ribs are provided with transversely extending grooves 127 opening downwardly therefrom at uniformly spaced intervals longitudinally of the belt so as to effectively define cogs for providing positive displacement power transmission. As shown in Figure 4, the reinforcing fabric 221 is buried within the distal portion 220 of the ribs so as to follow the configuration of the distal portion, including the grooves 227 in buried relationship to the entire lower surface of the ribs. As in the belt 13, a plurality of such fabric layers may be provided in the distal portion 220 of the ribs, as desired. Additionally, in each of the belts 113 and 213, short transverse fibers may be provided in the compression section outwardly of the reinforcing fabric layers to provide further improved lateral stability of the ribs. The elements of each of belts 113 and 213 which are similar to elements of belt 13 are identified by similar reference numerals but 100 and 200 higher, respectively. Each of the belts is similar and functions similarly, other than in the specific structural differences as discussed above. In each of the illustrated belts, the exposure of the reinforcing fabric buried in the distal portion of the ribs to the raw edge sides of the ribs permits the rib to pull away freely from the pulley and resultingly provides unexpected substantial reduction in noise in a power-transmitting operation of the belt. The provision of the cog grooves in the belt 213 provides improved flexibility in the belt, permitting the belt to be used with small diameter pulleys, while yet providing the highly improved noise reduction advantages of the invention. Each of the belt constructions assures the maintained relationship between the ribs longitudinally of the belt during the power transmitting operation while avoiding the need for high dimensional -accuracy, or low tolerance manufacture in effecting the highly desirable noise reduction, by effectively precluding differences in the speed of the rib portions relative to each other. The belt construction of the present invention provides a highly improved, low noise power transmission characteristic not found in the belts of the prior art as discussed above, and is adapted for a wide range of power transmission and control functions advantageously in applications where such low noise operation is a desideratum. The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

Claims: Claims 1. In a power transmission belt having a plurality of inner, transversely spaced, parallel raw edge ribs, an outer transversely extending portion to which said ribs are joined to define a multiple rib belt, and a plurality of longitudinally extending tensile cords, the improvement comprising at least one layer of transversely extending reinforcing fabric buried within the innermost compresssion portion of each rib and having side edges exposed at the raw edge rib sides. 2. In a power transmission belt having a plurality of winner, transversely spaced, parallel raw edge ribs, an outer transversely extending portion to which said ribs are joined to define a multiple rib belt, and a plurality of longitudinally extending tensile cords, the improvement comprising at least one layer of transversely extending reinforcing fabric buried within the innermostcompression portion of each rib and having side edges exposed at the raw edge rib sides, said tensile cords being disposed within a tensile body portion of the belt in said outer portion of the belt, and said belt defining grooves between said ribs extending outwardly from said innermost portion to inwardly adjacent said tensile body portion. 3. In a power transmission belt having a plurality of inner, transversly spaced, parallel raw edge ribs, an outer transversely extending portion to which said ribs are joined to define a multiple rib belt, and a plurality of longitudinally extending tensile cords, the improvement comprising at least one layer of transversely extending reinforcing fabric buried within the innermost compression portion of each rib and having side edges exposed at the raw edge rib sides, said tensile cords being disposed within a tensile body portion of the belt in said ribs adjacent said outer portion of the belt, and said belt defining grooves between said ribs extending out wardly from said innermost portion to said outer portion of the belt. 4. In a power transmission belt having a plurality of inner, transversely spaced, parallel raw edge ribs, an outer transversely extending portion to which said ribs rejoined to define a multiple rib belt, and a plurality of longitudinally extending tensile cords, the improvement comprising at least one layer of transversely extending reinforcing fabric buried within the innermost compression portion of each rib and having side edges exposed at the raw edge rib sides, said innermost compression portion of each rib defining a plurality of longitudinally spaced transverse downwardly opening grooves. 5. The power transmission belt of claims 1, 2, 3 or 4 wherein short transversely extending reinforcing fibers are provided in the compression portion of the ribs outwardly of said reinforcing fabric. 6. The power transmission belt of claims 1, 2, 3 or 4 wherein said buried fabric comprises a fabric having at least one of the following characteristics: (a) comprising a canvas fabric; (b) formed of cotton yarn; (c) including a warp formed of crimped nylon yarns-; (d) formed of yarns formed of a blend of cotton yarn and synthetic resin fibres; (e) includes a warp formed of crimped yarn; (f) comprises a warp and a woof having a crossing angle in the range of approximately 5 degrees to 150 degrees; and (g) is bias cut. 7. The power transmission belt of claims 1, 2, 3 or 4 wherein said buried fabric is covered with a layer of rubber defining the distal portion of said compression portion. 8. The power transmission belt of claims 1, 2, 3 or 4 wherein each said buried fabric layer includes a layer of rubber laminated thereto. 9. The power transmission belt of claim 4 wherein said reinforcing fabric overlies and is spaced outwardly of the grooves. 10. The power transmission belt of claim 4 wherein said grooves are arcuate, the grooves of the respective ribs being aligned transversely across the belt.

Inventors: IMAMURA, JUNGI
Applicants: MITSUBOSHI BELTING LTD.
Application year: 1981
Main classification: F16G5
IPC codes: F16G5