Two-piece pin and grommet

The fastener includes a pin and a grommet for attaching a primary panel to a secondary panel. The pin includes two dual-height finger assemblies and a circular flexible flange or umbrella head. A primary panel through a first range of thicknesses is sealingly engaged between the flexible flange and the fingers of a first height of the dual-height finger assemblies, and a primary panel through a second range of thicknesses is sealingly engaged between the flexible flange and the fingers of a second height in the dual-height finger assemblies. The pin further includes a male element with external serrated ridges. The male element engages a passageway in the grommet which includes an internal ridge for engaging the external serrated ridges. The grommet further includes a pair of spaced disks for engaging an opening in a secondary panel.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention pertains to a two-piece pin and grommet, particularly for the 
fastening of a trim panel to a primary panel. The pin includes a flexible 
flange which, in combination with dual-height finger assemblies, provides 
a sealing function. 
2. Description of the Prior Art 
In the prior art, it is known to provide a flexible flange or umbrella head 
as a sealing member in a pin and grommet or similar fastening device. A 
typical use of such a pin and grommet configuration is to secure a 
secondary panel, such as an automotive trim panel, to a primary panel, 
such as an automotive body panel. Examples of this include U.S. Pat. No. 
5,651,634, entitled "Connection Between a Support and a Plate Element", 
issued on Jul. 29, 1997 to Kraus and U.S. Pat. No. 5,689,863, entitled 
"Clip", issued on Nov. 25, 1997 to Sinozaki. With the use of such a 
flexible flange, as the panel thickness increased, tension would increase 
until the head flattened. This increased tension resulted in improved 
sealing characteristics with respect to water, dust and sound. However, 
with thinner panels, there was less tension and the sealing 
characteristics degraded. As tooling techniques only allow for a certain 
amount of flex under the flexible flange or umbrella head, the panel 
thickness range and sealing capabilities are limited. 
Fasteners with multiple height fingers to accommodate a variation in panel 
thicknesses are likewise known in the prior art, but have not provided 
adequate sealing such as is necessary in many applications, particularly 
automotive applications. 
OBJECTS AND SUMMARY OF INVENTION 
It is therefore an object of this invention to provide a fastener of a pin 
and grommet configuration for securing a secondary panel to a primary 
panel. 
It is therefore a further object of this invention to provide a fastener of 
a pin and grommet configuration which has improved sealing 
characteristics. 
It is therefore a still further object of this invention to provide a 
fastener of a pin and grommet configuration which can accommodate an 
increased range of primary panel thicknesses. 
These and other objects are attained by providing a fastener of a pin and 
grommet configuration wherein the pin includes a flexible flange or 
umbrella head which engages the primary panel immediately outwardly 
adjacent of the periphery of an aperture through which the pin passes. The 
flexible flange or umbrella head provides a sealing surface against the 
primary panel. Additionally, the pin includes a circular body with a 
diameter chosen to pass through the aperture of the primary panel. The pin 
further includes dual-height finger assemblies so that an increased range 
of primary panel thicknesses can be engaged while maintaining a strong 
seal with the flexible flange. A grommet attaches to the secondary panel 
and further attaches to pin at a variable location.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings in detail wherein like numerals refer to like 
elements throughout the several views, one sees that FIG. 1 is an exploded 
perspective view of fastener 10, including pin 12 and grommet 14. 
Additionally, optional washer 100 is shown in phantom. Pin 12 includes 
lower cylindrical base 16 with a lower circular chamfered edge 18. The 
diameter of cylindrical base 16 is chosen to be inserted through aperture 
202 in primary plate 200 as shown in FIGS. 2, 3 and 5. Saucer-shaped 
flexible flange 20 if formed at the upper edge 22 of cylindrical base 16. 
Flexible flange 20 includes a relatively horizontal section 24 (from the 
orientation of FIGS. 2, 3 and 4) which engages to the periphery of upper 
edge 22 of cylindrical base 16. Horizontal section 24 further supports 
downwardly extending umbrella section 26. 
Opposed sides of the cylindrical wall 27 of base 16 further include 
dual-height finger assemblies 28, 30. Dual-height finger assemblies 28, 30 
include lower fingers 32, 34, respectively, immediately adjacent to upper 
fingers 36, 38, respectively. Fingers 32, 34, 36, 38 are formed from the 
material of cylindrical wall 27 and extend upwardly and outwardly 
therefrom so as to point toward flexible flange 20. Fingers 32, 34, 36, 38 
further have sufficient elasticity so as to be urged toward cylindrical 
wall 27 as cylindrical base 16 is pushed through aperture 202 of primary 
panel 200 and then spring outwardly to an engaged position immediately 
outwardly adjacent from aperture 202 of primary panel 200 such as is shown 
in FIGS. 2 and 3. 
As shown in FIGS. 2, 3 and 5, primary plate 200 is engaged from above by 
flexible flange 20 and from below by either upper fingers 36, 38 (as shown 
in FIGS. 2 and 3) or lower fingers 32, 34. As further shown in FIGS. 2 and 
3, there is a limited range of thicknesses of primary panel 200 which can 
be accommodated by any one pair of fingers and flexible flange 20. FIG. 2 
illustrates a relatively thin primary panel 200 engaged by upper fingers 
36, 38 and flexible flange 20 wherein flexible flange 20 is not strongly 
pressed against primary panel 200 and a seal for particular applications 
is formed. FIG. 3 illustrates a relatively thick primary panel 200 engaged 
by upper fingers 36, 38 and flexible flange 20 wherein flexible flange 20 
is strongly pressed against primary panel 200 to the extent that flexible 
flange 20 has flattened near the level of horizontal section 24 and a 
relatively strong seal is formed. FIG. 3 illustrates the maximum thickness 
of primary panel 200 that can be effectively engaged by upper fingers 36, 
38 while maintaining a seal between flexible flange 20 and primary panel 
200. However, by engaging primary panel 200 between flexible flange 20 and 
lower fingers 32, 34, a range of increased thicknesses of primary panel 
200 can be effectively engaged while maintaining a seal of sufficient 
strength. Washer 100, shown in phantom in FIG. 1, may be optionally used 
in combination with fastener 10, and is typically placed between the 
interior portion of flexible flange 20 and primary panel 200. 
Immediately above cylindrical base 16 and flexible flange 20 is inwardly 
sloping conical wall 40 which leads to cylindrical male element 42. The 
tip 44 of cylindrical male element 42 is rounded and is upwardly adjacent 
from external serrated ridges 46. 
Grommet 14 includes lower and upper toroidal heads 50, 52 which are 
parallel to each other and spaced apart by cylindrical member 54. 
Cylindrical member 54 is hollow and lower toroidal head 50 is likewise 
hollow thereby forming passageway 56 through which pin 12 passes and is 
engaged. The lower portion of passageway 56 includes inwardly tapering 
wall 57 which is complementary to inwardly sloping conical wall 40 (see 
FIGS. 2 and 3). Passageway 56 extends into the tip 58 of grommet 14 with a 
shape complementary to cylindrical male element 42 and includes internal 
ridge 60 (see FIGS. 2 and 3) which engages external serrated ridges 46 of 
cylindrical male element 42. Passageway 56 terminates in aperture 63 which 
is bounded by internal ridge 60 and through which tip 44 of pin 12 passes 
in the installed position. The plurality of external serrated ridges 46 
allows for engagement to internal ridge 60 through a range of relative 
positions of pin 12 and grommet 14. 
Tip 58 includes longitudinal slot 62 which traverses internal ridge 60 and 
provides access to internal ridge 60. This allows for cleaning of internal 
ridge 60 and may allow the user to separate internal ridge 60 from 
external serrated ridges 46. 
In order to use fastener 10, the user typically engages lower and upper 
toroidal heads 50, 52 of grommet 14 about both sides of an aperture or 
slot 302 of secondary or trim panel 300 as shown in a doghouse 
configuration 304 in FIG. 5. The user additionally urges cylindrical base 
16 of pin 12 through aperture 202 of primary panel 200 and optionally 
through washer 100. The user positions pin 12 so that either upper fingers 
36, 38 or lower fingers 32, 34 snap engage against primary panel 200 at an 
appropriate position so that flexible flange 20 is flexed to an extent 
that a seal is formed between flexible flange 20 and primary panel 200. 
The fastener 10 may be supplied to the user with the uppermost external 
serrated ridge 46 engaged against the internal ridge 60. In such a 
configuration, the user then merely forces grommet 14 downward, if 
necessary, so that internal ridge 60 engages the desired external serrated 
ridge. However, if the pin 12 and grommet 14 are supplied to the user 
separately, the user then inserts tip 44 of element 42 of pin 12 into 
passageway 56 of grommet 14 and urges secondary or trim panel 300 toward 
primary panel 200 so that internal ridge 60 of passageway 56 engages 
external serrated ridges 46 of cylindrical male element 42 at an 
appropriate position along the range of possible engagements therebetween. 
Thus the several aforementioned objects and advantages are most effectively 
attained. Although a single preferred embodiment of the invention has been 
disclosed and described in detail herein, it should be understood that 
this invention is in no sense limited thereby and its scope is to be 
determined by that of the appended claims.