Retainer device and keyhole attaching arrangement

A one-piece plastic retainer device is provided for snap-in blind attachment in a keyhole-shaped apertured panel. The retainer device comprises a flat rectangular base having a push-in fastener shank adjacent one transverse edge. The shank extends from the base inner face while a fastener head and subjacent spacer collar extend from the base outer face in coaxial alignment with the shank. An integral wedge-shaped locking cam projects from the base outer face and is aligned on the base major axis of symmetry adjacent the base other transverse edge. The locking cam has a raised outboard facet and an inboard ramp sloped toward the fastener head with the facet spaced a predetermined longitudinal distance from a transverse outboard collar stop shoulder. The panel keyhole-shaped aperture is configured and dimensioned enabling the head to be initially inserted in the circular opening thereof. Upon the retainer being moved longitudinally into the slot the retainer is captured in a snap-in manner by virtue of the collar stop shoulder and the cam facet being positioned juxtaposed associated longitudinally opposed ends of the keyhole-shaped aperture.

BACKGROUND OF THE INVENTION 
This invention relates to a retainer device and keyhole attaching 
arrangement therefore and more particularly to a one-piece plastic 
retainer device having an integral pine-tree fastener with the device 
adapted for snap-in blind connection to a panel keyhole-shaped aperture. 
The prior art is replete with fastener arrangements for securing an 
apertured panel to an apertured support. The U.S. Pat. No. 3,119,476 
entitled Fastener Devices, dated Jan. 28, 1964, and U.S. Pat. No. 
3,271,059 entitled Clip For Fastening Together Two Apertured Panels, dated 
Sep. 6, 1966, both issued to A. S. Pearson are examples of two such 
arrangements. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an assembly between a 
one-piece plastic retainer device and a keyhole apertured panel in a blind 
snap-in manner. 
It is another feature of the present invention to provide an improved 
assembly of a one-piece plastic retainer device and a keyhole apertured as 
set forth above having a drive fastener shank adapted to be readily 
secured to a sheet-like support by being axially inserted in a support 
mounting hole. 
In accordance with a preferred embodiment of the invention, a decorative 
trim or applique panel is adapted to be supported on the outer face of a 
vehicle body underlying metal skin. The trim panel has its vertical ends 
formed with a return flange adapted to support a plurality of fasteners of 
the push-in pine-tree type such as shown in the U.S. Pat. No. 4,422,276 
issued Dec. 27, 1983 to Paravano or the U.S. Pat. No. 4,865,281 issued 
Sep. 12, 1989 to Woolar. Applicant's invention provides a one-piece 
plastic retainer device allowing ready blind snap-in attachment in a 
keyhole-shaped aperture in the panel return flange. The retainer device 
comprises a flat rectangular base having a push-in shank adjacent one 
transverse edge thereof so as to extend from the base bottom side. A 
collar extends from the base upper side and integrally supports in a 
spaced manner a fastener enlarged head in coaxial alignment with the 
shank. 
An integral locking cam projects from the base upper side and is aligned on 
the base major longitudinal axis of symmetry adjacent the base other 
transverse edge. The locking cam is formed with a raised arcuate outboard 
facet and an inboard ramp sloped toward the fastener head. The facet is 
spaced a predetermined longitudinal distance from a transverse collar stop 
shoulder positioned in opposed relation to the ramp. The panel return 
flange is formed with a keyhole-shaped aperture comprising a slot portion 
having a closed transverse edge terminating at its open end in a circular 
opening. The keyhole-shaped aperture is configured and sized enabling the 
retainer head to be initially inserted in the keyhole circular opening. 
Upon the retainer collar being moved longitudinally into the keyhole slot, 
the retainer is captured in a blind snap-in manner. This results by virtue 
of the collar stop shoulder and the cam facet being positioned juxtaposed 
associated longitudinally opposed ends of the keyhole-shaped aperture. 
Accordingly, the pine-tree stem projects normally from the return flange 
and is adapted for push-in insertion in an associated matching hole in the 
vehicle body skin.

DETAILED DESCRIPTION OF THE INVENTION 
Referring first to FIG. 1 there is shown a perspective view of a pick-up 
truck 10 having a tailgate 12 adapted for supporting an applique panel 14 
on outer sheet metal skin 16 of the tailgate by means of four holes 17. 
FIG. 2 shows the applique panel 14 provided with a plurality of retainer 
devices, generally indicated at 18, adapted for attachment to a vertically 
extending return flange 20 (FIG. 3) of panel 14. 
With reference to FIG. 8 the right hand return flange 20 is formed with a 
keyhole-shaped aperture, generally indicated at 21, including a 
longitudinally extending slot portion having parallel side edges 22 and a 
closed transverse edge 24. The slot portion terminates at its one open end 
in a circular shaped opening 26 having a center of curvature "C" and a 
predetermined diameter "D". The keyhole-shaped aperture has an overall 
longitudinal major dimension "L" measured between the slot closed end 24 
and longitudinally opposed arcuate locking edge portion 27 of opening 26. 
Thus, the keyhole shaped aperture 21 is configured and sized to receive 
the one-piece plastic retainer device 18 in a snap-in manner as will be 
explained below. 
As seen in FIGS. 3 and 6, the retainer device 18 comprises a flat 
rectangular base 30 defined by parallel side edges 31, an inner face 32, 
and an outer face 34, including a longitudinal axis of symmetry 36 (FIG. 
4). An integral fastener pine-tree type shank 38 projects normally from 
the inner face 32 with its principal axis 39 (FIG. 6) intersecting the 
base longitudinal axis 36 at right angles. It will be noted that the shank 
principal axis 39 is positioned longitudinally off-center as to be 
adjacent base one transverse edge 40 relative to base opposite transverse 
edge 41. The shank 38 is adapted for axial insertion in an associated 
mounting hole such as the hole 17 in the tailgate outer skin 16. 
FIGS. 9 and 10 show the retainer device 18 formed with fastener raised 
circular head 42 having its center aligned on the shank principal axis 39. 
The head 42 is joined to the base by a subjacent generally rectangular 
shaped raised collar (FIG. 9) projecting from the base outer face 34 and 
symmetrically disposed about the base major axis 36. The collar is formed 
with longitudinally extending parallel guide edges 44 spaced a 
predetermined transverse distance apart and terminating in a opposite 
parallel shoulders 45 and 46 with the leading outboard stop shoulder 45 
having lead-in chamfered corners 47. 
The fastener circular head 42, supported on the collar, provides a 
predetermined layered space between head undersurface 49 and the base 
outer face 34. The layered space is substantially equal to the thickness 
dimension of the return flange 20 establishing an interference fit upon 
the retainer device 18 being attached to the keyhole-shaped aperture 21. 
The fastener head 42 has a predetermined diameter the dimension of which 
is slightly less than the diameter "D" of the keyhole circular opening 26 
enabling the head 42 to pass therethrough. 
As best seen in FIGS. 9, 10 and 11 the base outer surface 34 is formed with 
an integral wedge-shaped locking cam 50 symmetrically disposed about the 
base longitudinal axis 36. The locking cam 50 has a raised arcuate facet 
52 extending normal to the base outer surface 34 and a ramp portion 54 
sloped in a longitudinal direction downwardly toward the fastener head 42. 
It will be noted in FIG. 9 that the arcuate facet 52 has a predetermined 
radius of curvature "R" with its center of curvature 56 located on the 
base longitudinal axis 36. 
With reference to FIGS. 9, 10, and 11 it will be noted that the fastener 
head undersurface 49 is formed with a C-shaped continuous chamfer having a 
half-circle segment 60 terminating in a pair of parallel trailing segments 
62. The chamfer half-circle segment 60 is adapted to engage the 
keyhole-shaped aperture cusps 66 allowing guided smooth insertion of the 
retainer device 18. 
To secure the panel 14 to the tailgate sheet-like support skin 16 the 
retainer device 18 is initially assembled with the panel return flange 20 
by gripping the shank 38 and inserting the head 48 through the 
keyhole-shaped aperture circular opening 26, as seen in FIG. 4, with the 
base one transverse leading edge 40 positioned substantially parallel to 
the slot transversely extending closed end 24. Upon the retainer device 
leading edge 40 being moved longitudinally toward the slot closed end 24 
the head chamfer segment 60 contacts the aperture cusps 66 which, together 
with the stop shoulder beveled corners 46, provide smooth lead-in travel 
of the collar into the slot until the collar transverse stop shoulder 45 
engages the slot closed end 24. 
During this longitudinal movement the raised locking cam 50 rides on the 
return flange outer surface until just prior to the collar stop shoulder 
engaging the slot closed end. This causes the trailing portion of the 
base, aft of the collar trailing shoulder 46, to be flexed outwardly thus 
biasing the head chamfer 60 into positive engagement with the return 
flange outer surface. FIG. 9 shows the locking cam facet 52 longitudinally 
spaced from the leading stop shoulder 45 a dimension "Y" which is a 
predetermined length less than the longitudinal maximum dimension "L" of 
the keyhole-shaped aperture 21. 
In the disclosed embodiment the maximum dimension "L" is about 1.0 mm 
greater than the dimension "Y" to provide tolerance clearances. Thus 
during attachment, immediately preceding the collar leading stop shoulder 
45 engaging the slot closed end 24, the locking cam snaps into the 
keyhole-shaped aperture circular portion 26. As a result of the facet 52 
is located juxtaposed arcuate portion 27 while the leading shoulder 45 is 
positioned juxtaposed the slot closed end 24 capturing the retainer devise 
in the keyhole-shaped aperture. 
It will be noted in FIG. 11 that the trailing or aft portion of the base 30 
is angled or canted outwardly from the plane of its inner surface 32 by a 
slight acute angle "X" of the order of five degrees. By virtue of having 
the base trailing portion canted outwardly the base trailing portion 
peripheral upper surface 34, adjacent side edges 31, is resiliently biased 
into contact with the return flange outer surface insuring a tight noise 
free connection of the retainer device in the keyhole-shaped aperture 21. 
Although only one embodiment of the invention has been illustrated and 
described, it is apparent that modifications and variations will readily 
come to mind of a person skilled in the art which modifications and 
variations do not fall outside the scope of the invention as defined by 
the following appended claims.