WO1998054939A1

WO1998054939A1 - System for fastening an assembly to a surface

Info

Publication number: WO1998054939A1
Application number: PCT/US1998/010192
Authority: WO
Inventors: James P. Scholz; E. Scott Martin
Original assignee: The Whitaker Corporation
Priority date: 1997-05-29
Filing date: 1998-05-19
Publication date: 1998-12-03
Also published as: AU7578798A; TW385883U

Abstract

An assembly (10) mountable onto surface such as of a circuit board (16). Nut fasteners (30, 32) are held captive in apertures (34) of the assembly to permit rotation as the nut fasteners are threaded onto bolts (22) of the circuit board and move vertically downward within the apertures during threading. A pair of latch projections (38) maintain the nut fasteners in the apertures (34) after assembly by being abutted by annular collars (46) at bottom ends of the nut fasteners, with one of the latch projections on a free end of a latch arm (50) that is outwardly deflectable during fastener insertion into the aperture.

Description

SYSTEM FOR FASTENING AN ASSEMBLY TO A SURFACE

The present invention relates to the field of fastening and more particularly to assemblies mountable to a surface.

In computers and other electronic equipment, circuit boards are utilized to which are mounted numerous electrical and electronic components. Smaller circuit cards are utilized to establish electrical connections to a larger circuit board in a manner that permits removal and disconnection, by inserting an edge of the card into a receptacle connector mounted on the board and containing an array of contacts connected to circuits of the board; contact sections of the contacts are exposed within a card- receiving cavity of the connector that engage circuit pads on the card surfaces upon card insertion. It has become useful to secure certain cards within larger modules so that components mounted on the card are protected by the module covers during handling. Such modules need to be accurately guided during mating with the receptacle connector so that the leading end of the enclosed card is accurately received into the card-receiving cavity of the connector, since the module covers inhibit accurate visual alignment of the card with the cavity. It is known to provide elongate guide members projecting from the board from ends of receptacle connectors to facilitate mating in similar situations. Such elongate guide assemblies may be mounted on the circuit board such as with bolts of the circuit board onto which are threadable nut fasteners of the guide assemblies that are rotatably held to the guide assemblies.

It is desired to provide a convenient, economical system for assembling the nut fasteners to the guide assemblies.

An assembly is mountable on the circuit board by nut fasteners that are held captive to the assembly in a manner permitting rotation of the nut fasteners for threading onto upstanding bolts of the circuit board. The nut fasteners are integral members that are disposed in apertures of mounting flanges of the assembly into which the bolts are received, and the apertures have a height permitting vertical movement of the nut fasteners to move from an unthreaded state to a fully threaded state. Annular collars at bottom ends of the nut fasteners each have an enlarged diameter so that the collar abuts a constriction at the top of the aperture to hold the nut fastener in the aperture. The constriction is defined by latching projections at the upper entrance to each aperture, at least one of which is disposed on the free end of a latch arm that deflects outwardly as the nut fastener is urged downwardly into the aperture and the collar rides over the latching projections. The assembly may be a guide assembly to guide mating of a card module to a receptacle connector of the circuit board.

An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings .

FIGURE 1 is an isometric view of the present invention with the fasteners exploded from the assembly; FIGURES 2 and 3 are enlarged isometric views of a portion of the assembly showing a fastener being assembled thereto; and

FIGURE 4 is a cross -sectional view of the assembly with a pair of fasteners assembled thereto, unthreaded and partially threaded to respective bolts of a circuit board, respectively.

Guide assembly 10 having a frame section 12 and guide sections 14, with the assembly mountable to a circuit board 16 (FIG. 4) around a receptacle connector (not shown) disposed within a connector- receiving cavity 18 of frame section 12. Guide sections 14 include opposed guide channels 20 along which slide side portions of a card- containing module (not shown) when the module is being moved to the connector for insertion of a card thereof into a card- receiving cavity of the receptacle connector with which the card must be aligned to become mated. Optionally, the guide sections may be initially separate members that are pivotably mountable to end sections of a frame member, whereby the guide sections may be pivoted to a recumbent position when a module is not mated with the receptacle connector. Preferably, the guide assembly is molded of plastic material such as polycarbonate resin. Optionally, the connector housing may be formed to include the frame and guide sections as integral portions thereof. The connector may be, for example, a Slot 1 Connector sold by AMP Incorporated, Harrisburg, PA under Part Nos. 145251-1 and -2. Fasteners 30,32 are utilized to secure the guide assembly to the circuit board by being threadable onto bolts 22 (FIG. 4) extending upwardly from the board 16. Fasteners 30,32 are movably held captive in respective apertures 34 of mounting flanges 36 at respective ends of guide assembly 10 by a pair of opposed latch projections 38 at the upper entrances 40 to apertures 34 and by smaller diameter aperture bottoms 42 defining bolt-receiving lower entrances 44. Latch projections 38 define a constriction at the upper entrances of the apertures 34 to be abutted by annular collars 46 at lower ends 48 of the fasteners. One of the latch projections 38 is disposed on the free end of a latch arm 50 that is defined along an outer wall by a pair of slots 52 extending downwardly toward the board-mounting surface of the mounting flanges 36. During assembly, each fastener 30,32 is urged into the apertures as annular collar 46 snaps past latch projections 38 when latch arm 50 is deflected outwardly, whereafter the latch arm resiles with both of the latch projections now above the annular collars. Each fastener 30,32 includes a threaded bolt-receiving hole 54 extending upwardly from lower end 48, and further includes a tool- engageable upper end 56. Fasteners 30 are shown to include a hexagonal tool -receiving cavity 58 in upper end 56 cooperable with a socket wrench, while fasteners 32 are shown to include slots 60 extending downwardly from upper end 56 cooperable with a screwdriver. Referring to FIG. 4, a pair of fasteners 30a, 30b are shown held in respective apertures 34a, 34b. Fastener 30a is shown in an uppermost position within aperture 34a and is unthreaded onto bolt 22a; annular collar 42a is abutting latch projections 38a. Fastener 30b is shown partially threaded onto bolt 22b and has moved concomitantly downwardly along aperture 34b. Bolts 22a, 22b are shown immovably affixed to circuit board 16 with threaded shafts 24a, 24b protruding upwardly through and beyond board apertures 26a, 26b, with heads 28a, 28b recessed within hexagonally shaped counterbores into the bottom surface of the board in a manner that prevents rotation of the bolts as the nut fasteners are threaded thereonto. Preferably, the height within the aperture within which the fastener is movable, corresponds with the length of the bolt shank extending upwardly from the top surface of the circuit board, so that the bolt shank is fully received into the aperture prior to the fastener being threaded thereonto and the assembly is mountable flush onto the circuit board top surface.

The arrangement of the present invention provides for the guide assembly to have integral means to hold the nut fasteners captive thereto, obviating the need for additional clips or other fastening accessories, while it permits substantial vertical float of the fasteners within respective apertures to permit threading over the shafts of the circuit board bolts.

Variations and modifications of the specific embodiment described herein, are possible that are within the spirit of the invention and the scope of the claims. For example, a pair of latch arms or three latch arms may be utilized spaced around the aperture entrance .

Claims

WHAT IS CLAIMED IS:

1. A system for affixing fasteners (30,32) to an assembly (10) of the type mountable onto a surface such as of a circuit board (16) , where the assembly (10) includes mounting flanges (36) with apertures (34) therethrough between board-moun ing and board- remote surfaces and the fasteners (30,32) are insertable into the apertures (34), characterized in that: each said fastener (30,32) has an annular collar (46) extending radially outwardly from side surfaces thereof and having a diameter less than a diameter of a respective said aperture (34) , each said aperture (34) has a fastener- receiving upper entrance (40) along said board- remote surface and a bolt-receiving lower entrance (44) along said board- mounting surface, said lower entrance (44) having a smaller diameter than that of said annular collar (46) of a said fastener (30,32), and each said upper aperture entrance (40) includes a constriction defined by at least a pair of opposed inwardly extending projections (38) and defining a distance therebetween less than the diameter of said annular collar (46) , and at least one said projection (38) being defined on a free end of an outwardly deflectable arm (50) , whereby a fastener is insertable into a respective aperture by deflecting the arm (50) outwardly until the annular collar (46) rides past the projections (38) and latches therebeneath, thus capturing the fastener in the aperture.

2. The system as set forth in claim l further characterized in that each said annular collar (46) is disposed at a lower end (48) of said fastener (30,32) and has a thickness substantially less than a distance between said latch projections (38) and said smaller diameter aperture bottom (42) , whereby said fastener (30,32) is permitted to be movable within said aperture (34) from an uppermost unthreaded position to a lowermost position when fully threaded onto an upstanding bolt shank (24) protruding into said aperture (34) through said bolt-receiving lower entrance (44) , as the fastener is threaded onto the bolt (22) .