Patent Application
20150164184
The invention relates to a mechanical fastener, and more particularly to an elastically deformable fastener for coupling matable components.
Currently, components which are to be mated together in a manufacturing process are subject to positional variation based on the mating arrangements between the components. One common arrangement includes components mutually located with respect to each other by 2-way and/or 4-way male alignment features; typically undersized structures which are received into corresponding oversized female alignment features such as apertures in the form of openings and/or slots. Alternatively, double-sided tape, adhesives or welding processes may be employed to mate parts. Irrespective of the precise mating arrangement, there is a clearance between at least a portion of the alignment features which is predetermined to match anticipated size and positional variation tolerances of the mating features as a result of manufacturing (or fabrication) variances. As a result, occurrence of significant positional variations between the mated components is possible, which may contribute to the presence of undesirably large and varying gaps and otherwise poor fit. The clearance between the aligning and attaching features may lead to relative motion between mated components, which contribute to poor perceived quality. Additional undesirable effects may include squeaking and rattling of the mated components, for example.
In one exemplary embodiment, a fastener for operatively coupling matable components is provided. The fastener includes a base portion. The fastener also includes a protrusion extending from the base portion, wherein the protrusion is formed of an elastically deformable material and is configured to elastically deform upon insertion through a first aperture of a first matable component and a second aperture of a second matable component, wherein the first aperture and the second aperture are aligned, and wherein the first matable component and the second matable component are retained to each other upon insertion of the protrusion through the first aperture and the second aperture.
In another exemplary embodiment, a fastener for operatively coupling matable components is provided. The fastener includes a base portion having a first side and a second side. The fastener also includes a first protrusion extending from the first side of the base portion, wherein the first protrusion is formed of an elastically deformable material and is configured to elastically deform upon insertion through a first aperture of a first matable component. The fastener further includes a second protrusion extending from the second side of the base portion, wherein the second protrusion is formed of an elastically deformable material and is configured to elastically deform upon insertion through a second aperture of a second matable component, wherein the first protrusion and the second protrusion are each configured to provide at least one of retention and alignment of the first matable component and the second matable component.
In yet another exemplary embodiment, an elastic retaining assembly for matable components includes a first component having a first aperture. Also included is a second component having a second aperture, wherein the second component is configured to be mated with the first component. Further included is an elastically deformable fastener configured to operatively couple the first component to the second component, the elastically deformable fastener having a base portion and at least one protrusion extending away from the base portion, wherein the at least one protrusion is formed of an elastically deformable material and is configured to elastically deform upon insertion with at least one of the first aperture and the second aperture, and wherein the first matable component and the second matable component are retained to each other upon insertion of the protrusion through the first aperture and the second aperture.
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.
Referring to
Referring to
Any suitable elastically deformable material may be used for the protrusion 18 and possibly the base portion 12 and/or the standoff 17 of the fastener 10. The term “elastically deformable” refers to components, or portions of components, including component features, comprising materials having a generally elastic deformation characteristic, wherein the material is configured to undergo a resiliently reversible change in its shape, size, or both, in response to application of a force. The force causing the resiliently reversible or elastic deformation of the material may include a tensile, compressive, shear, bending or torsional force, or various combinations of these forces. The elastically deformable materials may exhibit linear elastic deformation, for example that described according to Hooke's law, or non-linear elastic deformation.
Numerous examples of materials that may at least partially form the components include various metals, polymers, ceramics, inorganic materials or glasses, or composites of any of the aforementioned materials, or any other combinations thereof. Many composite materials are envisioned, including various filled polymers, including glass, ceramic, metal and inorganic material filled polymers, particularly glass, metal, ceramic, inorganic or carbon fiber filled polymers. Any suitable filler morphology may be employed, including all shapes and sizes of particulates or fibers. More particularly any suitable type of fiber may be used, including continuous and discontinuous fibers, woven and unwoven cloths, felts or tows, or a combination thereof. Any suitable metal may be used, including various grades and alloys of steel, cast iron, aluminum, magnesium or titanium, or composites thereof, or any other combinations thereof. Polymers may include both thermoplastic polymers or thermoset polymers, or composites thereof, or any other combinations thereof, including a wide variety of co-polymers and polymer blends. An example of a suitable polymer includes acetal (e.g., POM). In one embodiment, a preferred plastic material is one having elastic properties so as to deform elastically without fracture, as for example, a material comprising an acrylonitrile butadiene styrene (ABS) polymer, and more particularly a polycarbonate ABS polymer blend (PC/ABS), such as an ABS acrylic. The material may be in any form and formed or manufactured by any suitable process, including stamped or formed metal, composite or other sheets, forgings, extruded parts, pressed parts, castings, or molded parts and the like, to include the deformable features described herein. The material, or materials, may be selected to provide a predetermined elastic response characteristic of the fastener 10. The predetermined elastic response characteristic may include, for example, a predetermined elastic modulus and/or coefficient of friction.
Referring to
As will be apparent from the description herein, the elastically deformable nature of the fastener 10, in combination with the particular orientations described, facilitates precise alignment and retention of the first component 20 relative to the second component 22 by accounting for positional variation of the retaining and/or locating features of the components that are inherently present due to manufacturing processes. The self-aligning benefits associated with use of the fastener 10 will be described in detail below.
The first component 20 includes a first aperture 24 and the second component 22 includes a second aperture 26 that is to be aligned with the first aperture 24 upon mating of the components.
Reference is now made to
At the pre-assembly stage, as depicted in
At the partially assembled stage, as depicted in
At the assembled stage, as depicted in
As shown, the first component 20 and the second component 22 may include a plurality of apertures 24, 26 configured to receive a plurality of protrusions of a plurality of fasteners. Each of the plurality of apertures are positioned to correspondingly receive respective protrusions in a manner described in detail above. The elastic deformation of the plurality of elastically deformable protrusions elastically averages any positional errors of the first component 20 and the second component 22. In other words, gaps that would otherwise be present due to positional errors associated with portions or segments of the first component 20 and the second component 22, particularly locating and retaining features, are eliminated by offsetting the gaps with an over-constrained condition of other elastically deformable protrusions. Specifically, the positional variance of each protrusion and/or aperture is offset by the remaining protrusions to average in aggregate the positional variance of each protrusion. Elastic averaging provides elastic deformation of the interface(s) between mated components, wherein the average deformation provides a precise alignment, the manufacturing positional variance being minimized to Xmin, defined by Xmin=X/√N, wherein X is the manufacturing positional variance of the locating features of the mated components and N is the number of features inserted. To obtain elastic averaging, an elastically deformable component is configured to have at least one feature and its contact surface(s) that is over-constrained and provides an interference fit with a mating feature of another component and its contact surface(s). The over-constrained condition and interference fit resiliently reversibly (elastically) deforms at least one of the at least one feature or the mating feature, or both features. The resiliently reversible nature of these features of the components allows repeatable insertion and withdrawal of the components that facilitates their assembly and disassembly. In some embodiments, the elastically deformable component configured to have the at least one feature and associated mating feature disclosed herein may require more than one of such features, depending on the requirements of a particular embodiment. Positional variance of the components may result in varying forces being applied over regions of the contact surfaces that are over-constrained and engaged during insertion of the component in an interference condition. It is to be appreciated that a single inserted component may be elastically averaged with respect to a length of the perimeter of the component. The principles of elastic averaging are described in detail in commonly owned, co-pending U.S. patent application Ser. No. 13/187,675, now U.S. Publication No. U.S. 2013-0019455, the disclosure of which is incorporated by reference herein in its entirety. The embodiments disclosed above provide the ability to convert an existing component that is not compatible with the above-described elastic averaging principles, or that would be further aided with the inclusion of an elastically averaged alignment and retention system as herein disclosed, to an assembly that does facilitate elastic averaging and the benefits associated therewith.
Referring to
As described above in relation to other embodiments, at the partially assembled stage, the fastener 10, and more particularly the protrusion 42, is inserted into the apertures 26. The protrusion 42 includes a protrusion width that is greater than an aperture width of the apertures 26, thereby ensuring deformation of the protrusion 42 upon passing through the apertures 26. The larger protrusion width, relative to the aperture width, causes an interference condition during assembly that is overcome through elastic deformation as described herein.
At the assembled stage, further insertion of the fastener 10, and more specifically the protrusion 42, into the apertures 26 ultimately leads to a fully engaged position of the fastener 10. In the fully engaged position, a tight, fitted engagement between the fastener 10 and the apertures 26 is achieved by contact interface between at least a portion of the perimeter of the protrusion 42 and respective aperture walls 32 defining the apertures 26, thereby providing a retention force on the mated components. The interference between the protrusion 42 and the aperture walls 32 causes elastic deformation proximate the perimeter of the protrusion 42.
It is to be appreciated that numerous configurations of the fastener 10 may be employed, particularly with respect to the first protrusion 40 and the second protrusion 42. Specifically, any of the above-noted geometries may be used. Furthermore, any combination of such geometries may be employed. The illustrated embodiments of sphere-sphere (
The above-described embodiments advantageously enable two or more parts with aligned apertures to be mated with one or more elastically deformable fasteners in a manner that provides a tight fit and enhanced alignment, thereby improving overall consumer satisfaction. The embodiments of the fastener 10 described herein may be used to replace damaged push type fasteners, for example, which are often referred to in the industry as “Christmas tree” fasteners.
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.
