The present invention pertains generally to an improved pulley assembly and method for producing a pulley assembly.
It is well known to implement pulleys to transfer rotational energy from one device to another. Conventional pulleys are typically composed of cast iron or steel to support heavy loads and to resist wear. Cast iron and steel are, however, relatively heavy materials and pulleys composed of such materials are therefore also relatively heavy.
The pulley assembly of the present invention includes a ring portion having a radially outer frictional surface, and a radially inner ring flange defining a plurality of ring teeth. The pulley assembly also includes a hub integrally formed onto the ring portion. The hub has a peripheral hub flange that includes a top portion and a bottom portion configured to trap the ring flange therebetween. The hub flange is also configured to engage the ring teeth and thereby prevent rotation of the hub relative to the ring portion. The ring portion is preferably composed of a first material such as steel or cast iron, and the hub is preferably composed of a second material such as aluminum or magnesium that is lighter by volume than the first material. Accordingly, the overall weight of the pulley assembly is less than that of a comparable pulley assembly composed entirely of steel or cast iron.
A preferred method for manufacturing the pulley assembly initially includes providing an upper tool having an upper sealing lip, and a lower tool having a lower sealing lip. A ring portion having a ring flange is then disposed within the lower tool. The upper and lower tools are then engaged such that a cavity is formed therebetween. According to a preferred embodiment, the upper tool, the lower tool and the ring portion are heated. A compressive force is preferably applied to draw the upper and lower tools together and thereby clamp the ring flange between the upper sealing lip and the lower sealing lip. Thereafter, material is transferred into the cavity formed between the upper and lower tools such that a hub is formed onto the ring portion.
The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings.
Referring to the drawings, wherein like reference numbers refer to like components,
Referring to
An energy transfer device such as a belt engaged with a pulley tends to wear the pulley friction surface over time. Accordingly, the ring portion 12 is preferably composed of steel or cast iron as such materials provide good resistance to wear and are relatively inexpensive. It is well known; however, that steel and cast iron are relatively heavy materials and a conventional pulley assembly made exclusively of steel or cast iron is correspondingly heavy.
Referring to
The engagement of the hub flange 30 with the ring flange 20 has been described in accordance with a preferred embodiment wherein the ring flange 20 is trapped between opposing portions 32a, 32b of the hub flange 30. It should be appreciated; however, that according to an alternate embodiment of the present invention, the geometry of the flange 20 may be replaced with that of flange 30 and vice versa. In other words, the ring flange 20 may include opposing portions (not shown) configured to trap the hub flange 30 therebetween.
The hub 14 is preferably composed of a material that weighs less for a given volume (i.e., is less dense) than the material of the ring portion 12 such that the complete pulley assembly 10 weighs much less than a conventional pulley assembly composed exclusively of steel or cast iron. According to the preferred embodiment, the hub is composed of Aluminum having a density of 2,700 kg/m3 or Magnesium having a density of 1,738 kg/m3, which are significantly lighter by volume than, for example, Iron having a density of 7874 kg/m3. Additionally, as described hereinabove, the friction surface 16 of the pulley assembly 10 which is engaged by a device such as a belt is preferably composed of steel or cast iron such that the pulley assembly 10 has strength and durability characteristics similar to those of a conventional pulley assembly composed exclusively of steel or cast iron.
Referring to
Referring to
Having described the tooling and the apparatus of the present invention, the preferred method for manufacturing the pulley assembly 10 will hereinafter be described. The method of the present invention is preferably initiated by placing a ring element such as the ring portion 12 into the ring cavity 52 of the lower tool 42. The upper tool 40 and the lower tool 42 are then engaged to form the cavity 60. A compressive force is then preferably applied to draw the upper and lower tools 40, 42 together and thereby clamp the ring flange 20 between the sealing lips 46, 50 such that material introduced into the cavity 60 does not leak out. The upper and lower tools 40, 42, and the ring portion 12 are maintained at a predetermined elevated temperature such that molten material introduced into the cavity 60 does not prematurely cool upon contact with a relatively cold surface. Molten material such as aluminum or magnesium is then injected into the cavity 60 to form the hub 14 which is cast onto the ring portion 12 thereby producing the pulley assembly 10 (shown in
While the preferred method was described hereinabove, it should be appreciated that alternate and/or additional steps may be implemented as well. For example, instead of injecting molten material into the cavity 60, a semi-solid material may be introduced into the cavity 60 in accordance with the well known semi-solid forging process. Furthermore, after the pulley assembly 10 is removed from the lower tool 42, it may be necessary to perform processing steps such as, for example, machining the central aperture 26 and the key-hole 28 (shown in
While the best modes for carrying out the invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention within the scope of the appended claims.
This application claims priority to U.S. Provisional Patent Application No. 60/739,578 filed on Nov. 23, 2005.
Number | Date | Country | |
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60739578 | Nov 2005 | US |