The subject invention relates to housings incorporating asymmetric surface portions, and more particularly housing covers that incorporate asymmetric surface portions, and even more particularly engine front covers that incorporate asymmetric surface portions, as well as internal combustion engines that utilize such housings and covers.
Various housings and housing covers, including the outer or inner surface, or both surfaces, of an engine front cover near the front crankshaft seal, incorporate flat-panels. These flat panels are subject to various incident pressure waves during operation of the engine, including those transmitted through the engine oil and those transmitted through the air space over the engine oil, or a combination thereof. These pressure waves can create an “oil canning” mode, wherein the front cover of the engine itself becomes a source of noise, vibration or harshness (NVH) due to incident pressure waves, or the cover otherwise amplifies or reinforces incident pressure waves within the engine that originate at other sources and impinge upon the outer or inner surfaces of the front cover.
Various solutions have been offered to address this problem, including the addition of structural ribbing to increase the stiffness of the engine front cover near the front crankshaft seal; however, the ability to use this approach is limited due to the fact that this region of the engine is very crowded and the space envelope available for the front cover is limited. Thus, the ability to incorporate structural ribs to stiffen the engine front cover is also limited. NVH damping pads have also been added to the engine front cover to address this problem, but have a limited ability to attenuate all of the “oil canning” modes resulting from the incident pressure waves, as these pads are typically designed to damp or attenuate specific frequencies and must be applied at a predetermined location in order to damp the frequency(ies) for which they are designed. NVH damping pads also increase the cost of the front covers to which they are applied due to the material and labor costs associated with making them and the labor necessary to install them.
Accordingly, it is desirable to provide housings, and more particularly housing covers, including engine front covers, which have improved NVH performance by reducing the propensity of the housings to contribute to NVH during operation of the devices, such as internal combustion engines, with which they are employed.
In one exemplary embodiment, a housing is disclosed. The housing includes an asymmetric surface portion having a periphery, the asymmetric surface portion comprising a plurality of asymmetric surface sections disposed about the periphery, each asymmetric surface section having a surface contour differing from the surface contours of the other surface sections.
In another exemplary embodiment, an engine front cover is disclosed. The engine front cover includes a substantially circular asymmetric surface portion disposed concentrically about a crankshaft bore, the asymmetric surface portion comprising a plurality of asymmetric surface sections disposed substantially concentrically about the crankshaft bore, each asymmetric surface section having a surface contour differing from the surface contours of the other surface sections.
In yet another exemplary embodiment, an internal combustion engine is disclosed. The internal combustion engine includes an engine block having a rotatable crankshaft disposed therein. The internal combustion engine also includes an engine front cover sealingly disposed on a front end of the engine block, the front cover comprising a substantially circular asymmetric surface portion disposed concentrically about a crankshaft bore, the asymmetric surface portion comprising a plurality of asymmetric surface sections disposed substantially concentrically about the crankshaft bore, each asymmetric surface section having a surface contour differing from the surface contours of the other surface sections.
The above features and advantages and other features and advantages of the invention are readily apparent from the following detailed description of the invention when taken in connection with the accompanying drawings.
Other features, advantages and details appear, by way of example only, in the following detailed description of embodiments, the detailed description referring to the drawings in which:
The following description is merely exemplary in nature and is not intended to limit the present disclosure, its application or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.
In accordance with the exemplary embodiments of
The housing 10 may include any suitable housing, particularly a housing having a surface, including an inner surface 11 or an outer surface 13 (or both), which is subject to incident pressure waves from a working fluid to which the surface(s) is exposed, particularly housings 10 that are susceptible to resonance and flexure of a surface, or portion of a surface, which is exposed to the incident pressure waves. The housing 10 may have any suitable shape or size, and may be used for any application. The housing 10 may also include a portion of a housing, such as a cover or lid, which may be detachably attached to the housing, such as by the use of a threaded fastener(s), such as a threaded bolt 12 and associated nut and/or threaded (e.g.
The housing 10, such as engine front cover 20, includes an asymmetric surface portion 30 (or a plurality of portions (
The asymmetric surface portion 30 defines an asymmetric surface 40. The asymmetric surface 40 may be asymmetrically disposed with regard to any fixed reference, including longitudinal axis 42. The asymmetry is not just bi-lateral or multi-lateral asymmetry about longitudinal axis 42, but is more extensive. The asymmetric surface portion 30 includes a plurality of asymmetric surface sections 50 or segments disposed about the periphery 32. The asymmetric surface sections 50 may have any suitable shape and may be disposed about the periphery 32 in any suitable manner. In the embodiments of
Each asymmetric surface section 50 has a surface contour or shape differing from the surface contours or shapes of the other surface sections 50, including shape differences defined by a size difference of the section. For example, where the asymmetric surface sections 50 comprise substantially circular sectors, each of the substantially circular sectors may have a different circumferential size. That is, the length of the arc of each of the substantially circular sectors along the periphery 32 may be different. This is illustrated in
For example, in the embodiment of
In another example, in the embodiment of
In yet another example, in the embodiment of
The housing 10, such as an engine front cover 20, may be made from any suitable material, including metals, ceramics, cermets, engineering plastics, and combinations or composites thereof. In one embodiment, the housing 10 may be formed from a metal, including aluminum or an aluminum alloy, and more particularly may formed as a cast aluminum component. A metal housing 10 may have any suitable predetermined thickness. In certain embodiments, the thickness of the housing 10 may be a substantially uniform thickness and the asymmetric surface portion 30 may be formed on the inner surface 11 of the housing, and due to the substantially uniform thickness may be present on the outer surface 13 as a negative image, i.e. convex curved surface contours on the inner surface forming corresponding concave surface contours on the outer surface 13. Similarly, the asymmetric surface portion 30 may be formed on the outer surface 13 of the housing, and due to the substantially uniform thickness may be present on the inner surface 11 as a negative image, i.e. convex curved surface contours on the outer surface 13 forming corresponding concave surface contours on the inner surface 11. In one embodiment, a housing 10, including an engine front cover 20, formed from cast aluminum or an aluminum alloy may have a thickness of about 2 mm to about 8 mm, and more particularly about 3 mm to about 6 mm, and even more particularly about 3 to about 4 mm. The housing 10 may also comprise an engineering thermoplastic, including an engineering thermoplastic composite, such as an engineering thermoplastic fiber composite, where strengthening fibers may be incorporated as continuous fibers, discontinuous fibers, tows, felts, woven or non-woven fabrics and the like. The fibers may be formed from any suitable fiber materials, including metal, polymer, ceramic, mineral, carbon fiber materials and the like. In one embodiment, a housing 10, including an engine front cover 20, formed from an engineering plastic may have a thickness of about 2 mm to about 5 mm, and more particularly about 2 mm to about 3 mm, and even more particularly about 2.5 mm.
Without being limited by theory, the asymmetric surface sections 50 are configured to reflect a coherent incident wave front and produce an incoherent wave front. In another aspect, the asymmetric surface sections 50 are configured to prevent resonance or amplification of incident wave fronts and prevent “oil canning” modes from being established on the interior or exterior of the housing 10.
While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the application.
This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61/673,526 filed Jul. 19, 2012, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61673526 | Jul 2012 | US |