Patent Application
20080047392
A tortional vibration hub assembly for an internal combustion engine is described below in detail. The tortional vibration hub assembly has an internal mass design and includes a hub member formed from thermoplastic material containing reinforcing fillers, an inertia ring, a rubber insert, an end cap, and in alternate embodiments, a metal sleeve. The tortional vibration hub assembly eliminates the majority of machining required for a traditional cast iron, aluminum or steel torsional vibration dampers thus reducing cost. Also, by utilizing a high strength injection molded polymer material, a unique construction with an end cap to provide added structure and an internal mass construction costs are reduced. Internal mass designs have polyvee grooves as a part of the hub, not the inertia ring. The use of high strength polymer materials also eliminates the need for paint, lowering cost, and reduces parasitic inertia by reducing the weight of the hub. The use of polymer materials over metals also improves NVH characteristics (ringing) of the torsional vibration damper. Internal mass designs have inherently lower stresses on the rubber, allowing for the use of lower cost rubber. Internal mass designs also have an inherent “limp-home” failure mode where the car can still be driven home even if the inertia ring come off because the belt rides on the hub, not the inertia ring.
Referring to the drawings,
Referring to
An inertia ring 36 and a rubber insert 38 are positioned inside cavity 34 with rubber insert 38 located between inertia ring 36 and outer wall 26. Rubber insert 38, in one embodiment, is in strip form and press fit between outer wall 26 and inertia ring 36. In another embodiment, rubber insert 38 is a molded ring of rubber that is press fit between outer wall 26 and inertia ring 36. In another embodiment, rubber insert 38 is injection molded between outer wall 26 and inertia ring 36. In still another embodiment, rubber insert 38 is molded to hub member 24 or inertia ring 36 in a “dual shot” process. Rubber insert 38 is formed from any suitable rubber materials, for example, ethylene propylene diene monomer rubber (EPDM), styrene butadiene rubber (SBR), natural rubber, polybutadiene, acrylonitrile butadadiene rubber (NBR), and acrylic. Inertia ring 36 is formed from any suitable material, for example, steel, cast iron, or a filled thermoplastic material.
An end cap 40 formed from a thermoplastic material is attached to hub member 24 enclosing inertia ring 36 and rubber insert 38 inside cavity 34. End cap 40 is attached to hub member 24 by any known method, for example, by vibration welding, laser welding, adhesive bonding, spin welding, or other known methods of attachment commonly used between polymer based materials. In alternate embodiments, hub member 24 and end cap 40 include interlocking features to facilitate locating end cap 40 relative to hub member 24, to provide additional surface area for bonding, and/or to provide added strength.
In one embodiment, a metal sleeve 42 is insert molded onto center portion 30. Metal sleeve 42 is sized to receive the front end of crank shaft 18 (shown in
Suitable thermoplastic resins for use in molding hub member 24 end cap 40, and/or inertia ring 36 include, but are not limited to, polyamids, for example semi-crystalline polyamids, such as, nylon 66 and nylon 6 commercially available from General Electric Company, polyphenylene sulfides, polyphthalamides, polyethyl imides, and mixtures thereof. The reinforcing fillers used to reinforce the thermoplastic resin can be in the form of particles and/or fibers. Suitable fillers for use in reinforcing the thermoplastic resins include, but are not limited to metal fibers, metalized inorganic fibers, metalized synthetic fibers, glass fibers, graphite fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, aramid fibers, mineral fillers, and mixtures thereof. Suitable, non-limiting, examples of mineral fillers include barytes, barium sulfate, asbestos, barite, diatomite, feldspar, gypsum, hormite, kaolin, mica, nepheline syenite, perlite, phyrophyllite, smectite, talc, vermiculite, zeolite, calcite, calcium carbonate, wollastonite, calcium metasilicate, clay, aluminum silicate, talc, magnesium aluminum silicate, hydrated alumina, hydrated aluminum oxide, silica, silicon dioxide, titanium dioxide, and mixtures thereof. In one embodiment, the thermoplastic material includes about 20% to about 80% by weight of reinforcing fillers, and in another embodiment from about 30% to about 55% by weight of reinforcing fillers.
Tortional vibration hub assembly 12, described above, eliminates the majority of machining required for known cast iron, aluminum or steel torsional vibration dampers which reduces manufacturing cost. Also, the use of a high strength injection molded polymer material, a unique construction with an end cap to provide added structure and an internal mass construction manufacturing also contribute to the reduction of manufacturing costs. Internal mass designs have polyvee grooves molded into the hub, not machined into the inertia ring. The use of high strength polymer materials also eliminates the need for paint, lowering cost, and reduces parasitic inertia by reducing the weight of the hub. The use of polymer materials over metals also improves NVH characteristics (ringing) of the torsional vibration damper. The internal mass design of tortional vibration hub assembly 12 provides for an inherent “limp-home” failure mode where the car can still be driven home even if the inertia ring come off because the accessory belt rides on the hub, not the inertia ring.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
