IMPROVED PLASTIC PULLEYS

Abstract: An improved plastic pulley capable of dissipating frictional heat thereby increasing belt life and reducing the wear of the surfaces of the pulley. A shaped metal ring (22) is disposed on the plastic surface of the pulley sheave (20) which contacts the belt (23).

Description: IMPROVED PLASTIC PULLEYS BACKGROUND OF THE INVENTION In recent years, in an effort to reduce the weight of automo¬ biles, attempts have been made to utilize pulleys made of plastic. V-belt pulleys have the advantage that the natural wedging effect developed by the V-configuration of such belts reduces slip- page and provides higher torque. However, this wedging action creates frictional heat which is capable of raising the tempera¬ ture of both the belt and the pulley. With plastic pulleys, suf¬ ficient heat can be generated to result in ultimate failure of the belt, as well as excessive wear on the surfaces of the pulley in contact with the belt. Plastic pulleys also suffer by virtue of the wear caused by the -abrading action of dust and grit particles that lodge between the belt and pulley surface. Another form of pulley is the cog belt pulley which has tooth¬ like projections on the outer periphery of the pulley which engages a cog belt which has projections which mate with the corresponding projections of the pulley. Such pulleys are also susceptible to heating up and excessive wear of the meshing surfaces. Accordingly, it is an object of this invention to provide im¬ proved plastic pulleys that are capable of dissipating the afore- mentioned frictional heat thereby increasing belt life and reducing the wear of the surfaces of the pulley. SUMMARY OF THE INVENTION In accordance with this invention, there is provided an im¬ proved plastic pulley wherein a shaped metal ring is disposed on the plastic surface of the pulley which contacts the belt. The metal ring is formed on the pulley by placing a shaped metal ring of a formed metal or light gauge steel in a mold having the con¬ figuration of the pulley and thereafter molding the plastic in the form of the desired pulley. Molding can be accomplished by injection, compression and transfer molding processes. O PI In this manner it is possible to form pulleys of any con¬ figuration which have the shaped metal ring of the invention. Thus, the pulleys can be formed in the configuration of (1) a single sheave pulley, or (2) a pulley having a multiple of in- dividual sheaves each adapted to receive a separate V-belt re¬ ferred to as a multi-V pulley, or (3) a sheave adapted to receive a single belt having more than one V-groove and referred to as a poly-V pulley. Also contemplated are cog-belt pulleys. Combina¬ tions of these configurations are also contemplated. BRIEF DESCRIPTIONS OF THE. DRAWINGS Figure 1 illustrates a cross-sectipnal view of one embodiment of the V-belt pulley of the invention. Figure 2 illustrates a view, partially in cross-section of a metal V-shaped ring for use with t.he V-belt pulley of Figure 1. Figure 3 illustrates a cross-sectional view of another embodi¬ ment of the invention. Figure 4 illustrates a cross-sectional view of another embodi¬ ment of the invention. Figure 5 illustrates a close-up view of a portion of the em- bodiment of the invention shown in Figure 4. Figure 6 illustrates a view, partially in cross-section, of a metal V-shaped ring for use with the V-belt pulley of Figures 4 and 5. Figure 7 illustrates another embodiment of the invention. Figure 8 illustrates a close-up view of a portion of the em¬ bodiment of the invention shown in Figure 7. Figure 9 illustrates a cross-sectional view of a portion of the embodiment of the invention shown in Figures 7 and 8. Figure 10 illustrates a cross-sectional view of another em- bodiment of the V-belt pulley of Figure 1. Figures 11 and 12, illustrate views, partially in cross- section, of metal V-shaped rings for use with the V-belt pulley of Figure 10. Figure 13, illustrates a cross-sectional view of a modifica- tion of the V-belt pulley of Figure 3. Figure 14, illustrates a cross-sectional view of a modifica¬ tion of the embodiment of the pulley of Figure 14. Figure 15, illustrates a close-up view of a portion of the embodiment shown in Figure 14. Figure 16, illustrates a view partially in cross-section, of a metal V-shaped ring for use with the V-belt pulley of Figures 14 and 15. - DESCRIPTION OF PREFERRED EMBODIMENT Referring to the Figures, one embodiment of the invention is illustrated in Figure 1 which shows a cross-sectional view of a single sheave plastic pulley having a metal V-shaped ring accord¬ ing to the invention. The pulley assembly 10 is comprised of hub means 11, sheave means 13 and V-shaped ring 21. The hub 11 has a central mounting hole 15 and one or more auxiliary mounting holes 17 positioned around the circumference of the hub 11. In this em¬ bodiment, the sheave means 13 has one V-groove 19 adapted to re¬ ceive a belt 23. The exterior surface of the V-groove 19 is pro¬ vided with a metal V-shaped ring 21 positioned so that the belt 23 is in contact with the metal surface of ring 21. Figure 2 illustrates a more detailed view of the metal V- shaped ring 21 used in conjunction with the V-belt pulley assem¬ bly 10. As illustrated, the V-shaped ring 21 is a continuous rim of metal shaped to form the inner surface of the plastic V-groove of the sheave means depicted in Figure 1. In Figure 2, there is illustrated in the lower portion 27 the actual appearance of the metal V-shaped ring as it would appear apart from the V-belt pulley assembly. The upper portion 25 of the figure shows the back side of the ring 21 and a cross-section through the ring 21 to show the thin wall of the ring 21. Groove surface 29 is in contact with the drive belt (not shown in Fig. 2) during operation of the pulley. Figure 3 illustrates another embodiment of the improved pulley of the invention. In Figure 3, the V-belt pulley assembly 30 is comprised of the hub means 11 having a central mounting hole 15 and one or more auxiliary mounting holes 17. However, in this embodi- ment, the sheave means 13 is comprised of three sheaves, each hav¬ ing a V-groove 19, a V-shaped ring 21 and adapted to receive a belt 23. In this embodiment, the metal V-shaped rings are similar to that illustrated in Figure 2. - Figure 4 illustrates another embodiment of the improved pulley of the invention. Figure 4 shows a cross-sectional view of a plas¬ tic pulley adapted to have a single belt with a plurality of V- shaped grooves on the under side of the belt and a corresponding set of V-shaped grooves in the sheave of the plastic pulley. Such a pulley assembly is referred to as a poly-V belt pulley. The pul- ley assembly 40 is comprised of hub means 41, sheave means 43 and a metal V-shaped ring 51. The hub 41 has a central mounting hole 45 and one or more auxiliary mounting holes 47 positioned around the circumference of the hub 41. In this embodiment, a sheave means 43 has a multiple of V-grooves 49 adapted to receive a drive belt (not shown in this Figure). The exterior surface of the V-groove 49 is provided with a metal V-shaped ring 51 positioned so that the drive belt is in contact with the metal ring 51. Figure 5 illustrates a more detailed view of the sheave means 43 of pulley assembly 40. Figure 5 illustrates the hub means 41 and shows an enlarged view of the V-shaped ring 51 in relationship O P to the V-grooves 49 and the drive belt 53. The edges of the ring 51 protrude into the plastic sheave means and the edges are pro¬ vided with several crimps 52 around the periphery of the ring 51 to prevent slippage of the metal ring. Figure 6 illustrates a more detailed view of the metal V- shaped ring 51 used in conjunction with the poly V-belt pulley assembly 40 illustrated in Figures 4 and 5. Figure 6 shows a cut away view showing the V-shaped ring 51 in a partial sectional view which exposes the inside surface of the V-shaped ring. The edge is crimped such as at 52 to prevent the ring from slipping on the plastic pulley. Figure 7 illustrates another embodiment of the improved pulley of the invention as it ' relates to cog-belt pulleys. Figure 7 shows a side view of a cog-belt pulley which has a plurality of tooth- like projections disposed around the outer periphery of the pulley which are adapted to receive and engage a drive belt (not shown in Figure 7). The cog- elt pulley 60 is provided with hub means 61 which has a central mounting hole 65. The rim of the cog-belt pul¬ ley is provided with a plurality of tooth-like projections 75 and around its outer circumference. The exterior surface of the pro¬ jections 75 is provided with a metal ring 71. Figure 8 shows a close-up view of the cog-belt pulley 60 which shows in greater detail the rim 63 having a plurality of projections 75 whose plastic surfaces 69 are molded against the metal ring 71. Also shown in this view is the drive belt 73 which has projections 77 which mesh with the metal ring 71. The metal ring is provided with several crimped edges 79 which pro¬ trude into the plastic to prevent slippage of the metal ring. Figure 9 shows a cross-sectional view of the cog-belt pulley assembly 60 which depicts hub means 61, rim 63 and a portion of the metal ring 71. The ring 71 is embedded into the edge of rim 81 such as shown at 83. The crimped edge 79 is also shown. Figure 10 shows the single sheave plastic pulley of Figure 1 having a modified V-shaped ring 22 which is formed such that the metal ring extends to cover and protect against damage the flange, i.e., the outwardly protruding portion of the sheave means 13. Figure 11 illustrates a more detailed view of the metal V- shaped ring 22 used with V-belt assembly 20. Ring 22 can be a continuous rim of metal such as depicted in Figure 2, However, as illustrated in Figure 11, V-shaped ring 22 is a continuous rim of metal except for the opening or gap 28. Such an open rim or ring can be produced by drawing a metal-strip through a suitable die and then forming the formed rim into a circular coil like a spring. The open rim or ring can be welded to form a solid ring. However, the open ring can be employed in the mold to form the plastic pulley. In this case, anchor tabs 34 are provided to anchor the metal insert to the plastic pulley. Figure 12 shows another alternative V-shaped ring 24 which can be a continuous ring such as in ring 21 of Figure 2. or split as in open ring 22 of Figure 11. V-shaped ring 24 is provided with slots 30 which fill with plastic when the plastic pulley is molded against the interior of ring 24 thereby providing means for anchoring the ring 24 onto the plastic pulley. The slots may be elongated as shown or have other shapes such as round. Figure 13 illustrates another embodiment 32 of the plastic pulley of Figure 3. In this embodiment the V-shaped rings 22 and 26 are formed so that the metal ring extends to cover and protect against damage the flanges of the sheave means 13. In this embodiment, the V-shaped ring 22 such as depicted in Figure 11 can be replaced by ring 24 of Figure 12. Figure 14 illustrates another embodiment of the pulley of Figure 4. In this embodiment metal V-shaped ring 55 is formed * ΕE OM so that the metal ring has extensions 56 to cover and protect against damage the flanges of the sheave means 43 of pulley assembly 42. Figure 15 illustrates a more detailed view of the sheave means 43 of pulley assembly 42. An enlarged view of the V-shaped ring 55 is shown with extensions 56. Figure 16 illustrates a more detailed view of the metal V- shaped ring 55 with extensions 56 used in conjunction with the poly V-belt assembly 42 illustrated in Figures 14 and 15. Figure 16 shows a cutaway view showing the V-shaped ring 55 in a partial sectional view which exposes the inside surface of the V-shaped ring. The edge is crimped such as at 52 to prevent the ring from slipping on the plastic pulley. Alternatively, the ring can be split such as illustrated- n Figure 11 or can be provided with holes as illustrated in Figure 12 to assue that the ring does not slip on the plastic pulley. Anyembodiment of the invention can be provided with one or more crimped edges such as shown as -52 in Figures 6 and 16. The plastic portion of the pulleys of the invention can be made from either thermosetting or thermoplastic materials. Suit¬ able thermoset polymers include the well-known phenolic resins prepared by reacting a phenol with an aldehyde such as formalde¬ hyde. Such resins are normally cured with a curing agent such as hexamethylene-tetramine. The phenolic resins of various grades can be employed such as heat resistant, improved impact, as well as gen¬ eral purpose. The various product forms can also be employed such as nodular, granular, flake and bulk molding materials. Other thermosetting resins such as polyesters can be employed in various forms such as granular, nodular, bulk molding compounds and sheet molding compounds. Epoxy resins can also be employed. Suitable thermoplastic materials are generally the plastics known as engineering thermoplastics and include such polymers as the polyarylates, such as polyesters of iso and terephthaloylchlorid and bisphenol-A; polybutyl terephthalate; polycarbonates, and poly- amides such as nylon. The plastic materials are frequently reinforced with fibers and filler. The preferred fibrous materials are glass fibers in the form of chopped fibers, strands or roving. A wide variety of fillers can be employed such as, but not limited to, silica, cal¬ cium carbonate, talc, quartz powders, clay, mica, carbon black, wood flour, wool and cotton flock, and the like. Such fibers and fillers are generally employed in a proportion of about 20 to about 70 percent by weight of the total plastic composition. The shaped ring of the invention can be fabricated of any metal or alloy that can be formed into a thin walled rim having a smooth surface and sufficient strength for the purpose intended. Suitable metals include steel, aluminum and brass. The wall thick¬ ness is generally in the range of about 0.010 to 0.100 inch. To further illustrate the invention, shaped metal rings such as shown in Figure 2 are manufactured from spun steel and have a thickness of 0.030 inch. The shaped metal rings are placed in a mold having the configuration of the pulley depicted in Figure 1. Then molding compounds described in Tables I and II are placed in the mold in successive molding runs and cured under the conditions shown to form plastic pulleys having the metal V-shaped ring of the invention. The pulleys are placed in service with conventional rubber V-belts. It is found that the V-belt pulleys exhibit a much greater life than similar belts used with a plastic pulley not having the V-shaped ring of the invention. Less wear of the pulley surface is also observed. _ OM While the invention has been illustrated using an all-plastic pulley, it is understood that the invention is also applicable with other pulley configurations which have a plastic sheave. Among such alternatives is the composite metal and plastic pulley of US Patent 3,772,928, the disclosure of which is hereby incor¬ porated by reference. TABLE EXAMPLE NO. Components: (parts by weight) Novolak resin 45 39 Hexamethylenetetramine 8 7 Wood flour 37 — Cotton fibers — 8 Clay 4 40 Lime 3 3 Zinc stearate 1 1 Nigrosine dye 2 2 Molding Conditions: Pressure (psi) 5 ,000 2 , 500 Temperature (°F.) 340 360 TABLE II EXAMPLE NO. Components: (parts by weight) Unsaturated polyester resin 20 Styrene monomer 7 Fiberglass (1/4 inch chopped) 20 Calcium carbonate 49.5 Calcium stearate 2 Carbon black 0.5 Tert-butyl peroxide 1 Molding Conditions: Pressure (psi) 2 ,000 Temperature ( F.) 310 __ O Λ ~ " I

Claims: I CLAIM: - 1 - In a plastic pulley, the improvement comprising a metal shaped ring disposed on the plastic surface of the pulley which contacts a belt. - 2 - A V-bel t pull ey in accordance with Claim 1. - 3 - The pulley of Claim 2 wherein the metal shaped ring is continuous. - 4 - The pulley of Claim 2 wherein the metal shaped ring is split. - 5 - The pulley of Claim 3 wherein the metal shaped ring is provided with slots which engage the plastic surface of the pulley. - 6 - The pulley according to Claims 3, 4 or 5 wherein the metal shaped ring extends to cover the flange of the plastic surface of the pulley. - 7 - The pulley of Claim 2 wherein the sheave means comprises a single sheave adapted to receive a V-belt. - 8 - The pulley of Claim 2 wherein the sheave means comprises more than one sheave each adapted to receive a separate V-belt. - 9 - The pulley of Claim 2 wherein the sheave means comprises a sheave adapted to receive a single belt having more than one V- groove. _ O PI - 10 - A cog-belt pulley in accordance with Claim 1. - 11 - The pulley of Claim 1 wherein the plastic comprises a phenolic resin molding material. - 12 - The pulley of Claim 1 wherein the plastic comprises a poly¬ ester molding material. O PΓ fy r. mIPrOj

Inventors: EMMETT J
Applicants: EMMETT J, HOOKER CHEMICALS PLASTICS CORP, HOOKER CHEM & PLASTICS CORP
Application year: 1980
Main classification: F16H55
IPC codes: F16H55