Patent Application
20130071203
The invention relates to fastener retention devices.
When a first component that is sensitive to vibration must be mounted to a second component that produces vibrations, elastic isolators may be used in conjuction with a bolt or other threaded fastener to connect the first and second components. The elastic isolators act to absorb vibrations from the second component, thereby limiting the exposure of the first component to vibration.
An apparatus includes structure having a first surface and a second surface, and defining a hole having a first opening at the first surface and a second opening at the second surface. A first member extends into the hole through the first opening and defines a first aperture. A second member extends into the hole through the second opening and defines a second aperture. A threaded fastener is at least partially disposed within the first and second apertures, and is selectively rotatable about an axis. A retainer member is disposed within the first and second apertures and resists axial movement of the first and second members and the threaded fastener.
The retainer member thus retains the first member, the second member, and the third member together prior to, and during, attachment of the apparatus to another member.
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 assembly 10 also includes a fastener system 30 to secure the first member 12 to the second member 14. The fastener system 30 includes a first member, namely, a first compression limiter 32, which extends into the hole 22 through the first opening 24. The fastener system 30 also includes a second member, namely, a second compression limiter 34, which extends into the hole 22 through the second opening 26.
The first compression limiter 32 includes a first wide portion 36 and a first narrow portion 38. The second compression limiter 34 includes a second wide portion 40 and a second narrow portion 42. In the embodiment depicted, the first and second wide portions 36, 40 are generally cylindrical and are wider than the hole 22. More specifically, in the embodiment depicted, the first and second wide portions 36, 40 are annular and have an outer diameter that is larger than the diameter of the hole 22. Accordingly, the first and second wide portions 36, 40 are outside the hole 22. In the embodiment depicted, the first and second narrow portions 38, 42 are hollow cylinders and are narrower than the hole 22; more specifically, the outer diameters of the narrow portions 38, 42 are smaller than the diameter of hole 22. The narrow portions 38, 42 are at least partially disposed within the hole 22.
The first compression limiter 32 includes a first inner surface 46 that defines a first aperture 50. In the embodiment depicted, the inner surface 46, and, correspondingly, the aperture 50, is cylindrical. The aperture 50 extends through the first wide portion 36 and the first narrow portion 38 of the first compression limiter 32, and is centered along axis 28. The second compression limiter 34 includes a second inner surface 54 that defines a second aperture 58. In the embodiment depicted, the inner surface 54, and, correspondingly, the aperture 58, is cylindrical. The aperture 58 extends through the second wide portion 40 and the second narrow portion 42 of the second compression limiter 34, and is centered along axis 28.
The fastener system 30 includes a threaded fastener 62, which, in the embodiment depicted, is a bolt having a head portion 66 that is characterized by a generally polygonal cross-sectional shape. In the embodiment depicted, the head portion 66 is generally hexagonal, though other cross-sectional shapes may be employed within the scope of the claimed invention. The threaded fastener 62 also includes a threaded shank 70 that is rigidly connected to the head portion 66. The shank 70 of the threaded fastener 62 is at least partially disposed within the first and second apertures 50, 58. The threaded fastener 62 is selectively rotatable about the axis 28.
A first elastomeric isolator member 74 is disposed between the first surface 18 and the wide portion 36 of the first compression limiter 32. A second elastomeric isolator member 78 is disposed between the second surface 20 and the wide portion 40 of the second compression limiter 34. In the embodiment depicted, the elastomeric isolators 74, 78 are annular, with each elastomeric isolator member 74, 78 surrounding a respective narrow portion 38, 42. The elastomeric isolators 74, 78 isolate the first member 12 from vibrations transmitted from the second member 14 when the fastener system 30 connects the first member 12 to the second member 14.
The fastener system 30 also includes a retainer member 82 that is disposed within the first and second apertures 50, 58. The retainer member 82 holds the fastener system 30 together during transportation of the prefabricated assembly 10 and during connection of the first member 12 to the second member 14. In the absence of the retainer member 82, gravity may cause the separation of the fastener 62 and the first and second compression limiters 32, 34. The retainer member 82 holds the fastener system 30 together by resisting or limiting axial movement of the first and second compression limiters 32, 34 and the threaded fastener 62.
Referring to
The inner surface 90 is similarly characterized by a plurality of alternating convex portions 102 and concave portions 106. The convex portions 102 and the concave portions 106 extend axially along the length of the retainer member 82. In the embodiment depicted, the retainer member 82 includes four concave portions 106 and four convex portions 102. The convex portions 102 are evenly spaced around the periphery of the retainer member 82; each concave portion 106 interconnects two of the convex portions 102.
Referring specifically to
The interaction between the convex portions 94 and the inner surfaces 46, 54 generally restricts movement of the first and second compression limiters 32, 34 (relative to each other) to axial movement (i.e., parallel to axis 28) and, optionally, to rotation about axis 28. Thus, referring again to
Referring to
The projections 118 that are disposed within the first concavity 122 and the first lip 126 are positioned so that contact between the projections 118 and the first lip 126 limits movement of the first compression limiter 32 in the first axial direction 110. Similarly, the projections 118 that are disposed within the second concavity 130 and the second lip 134 are positioned so that contact between the projections 118 and the second lip 134 limits movement of the second compression limiter 34 in the second axial direction 114.
More specifically, as shown in
As shown in
The compressibility of the members 74, 78 results in axial movement of the compression limiters 32, 34 toward one another until they contact one another, as shown in
Referring again to
The threaded fastener 62 is then inserted into the retainer member 82; as the threaded fastener 62 is inserted, the shank 70 exerts a radially-outward force on the convex portions 102, thereby causing some elastic deformation of the retainer member 82. Accordingly, the convex portions 102 exert a radially-inward spring force on the shank 70, which increases the frictional resistance between the shank 70 and the convex portions 102.
The retainer member 82 in the embodiment depicted has a low compressive yield, and thus does not hinder the tightening of the threaded fastener 62 to achieve the required clamp load of the bolt-to-isolator grommet-to-engine interface. In one embodiment, the retainer 82 is made of thermoplastic elastomer material. The retainer member 82 acts independently of the fastener 62 to retain the compression limiters 32, 34 with respect to each other, and thus also to retain the isolator members 74, 78, which are trapped between the structure 16 and the wide portions 36, 40. Accordingly, the compression limiters 32, 34 and the elastomeric isolator members 74, 78 will still remain together as assembled even if the threaded fastener 62 is removed or inadvertently bumped or jostled.
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.
