Thermal Expansion Retention Clip
FIELD OF THE INVENTION
The present invention relates to extruded, modular panel units for the
construction of walls, ceilings, roofs, canopies and windows, particularly of lighttransmitting
sections. More specifically, the invention discloses a retention clip used to
fasten such systems to metal constructions (i.e. purlins) while allowing for thermal
expansion of the panels.
BACKGROUND OF THE INVENTION
US Pat. No. 7,661,234 to Voegele, Jr. is one of a large family of patents all
directed to a panel assembly 10 as shown in Fig. 1 comprising a pair of juxtaposed
panels 11, 12 each having at a mating edge thereof a respective upright joining flange
13, 14 that support a sealing cap 15. The panel assembly 10 includes a retention clip 20
that serves both to fixedly attach the panel assembly 10 to a support structure 2 1 by
means of a bolt 22 as well as separating the mating edges of the panels so as to allow for
thermal expansion. The retention clip 20 employs a first generally Z-shaped plate 25
and a second generally C-shaped shape 26 which are co-operatively mounted to define a
pair of webs or uprights 27 and 27' supported at their lower ends by a common base 29
and defining at their upper ends opposing flanges 30 and 31.
The uprights 27 and 27' define opposing first and second surfaces that engage
opposing first and second ends of a pair of first and second adjacent panels, i.e. the
panels 11 and 12. Thus, the first and second ends of the adjacent panels are separated by
the respective first and second surfaces 27 and 27', which themselves define an inter
vening gap 32. Thermal expansion of the panels exerts pressure on the respective first
and second surfaces of the upright, thereby flexing them towards each other and
narrowing the gap without causing the panels to buckle.
The gap 32 between the panels is maintained by a spacer element 33, which
ensures that the panels 11 and 12 do not bear tightly against the uprights 27 and 27'. The
gap 32 is sufficient to allow longitudinal movement of the panels 11 and 12, such as
may result from thermal expansion and contraction of the panels and the sealing cap 15,
without causing significant frictional contact between the panels 11 and 12 and the
uprights 27 and 27'.
US Pat. No. 7,788,869 also to Voegele, Jr. discloses a similar retention clip but
wherein the gap may be maintained by an optional fin that projects downward from the
sealing cap and splays apart the uprights 27 and 27'.
The retention or fastening clips taught by Voegele, Jr. are based on two-part
constructions that require aligning prior to assembly.
US Pat. No. 6,164,024 to Konstantin shows various retention clips formed for
the most part of a single molding. Typically clip is an integral extrusion and can take on
a variety of forms in each of which the clip top flange extends continuously from one
side of the web to the other so as to be resistant to being bent upward on either side of
the web. The clip can be extruded with thickened portions to strength and its base can
be integral with the lower supporting structure.
In use, the base of the clip is fastened usually with bolts to the purlin or rafter of
the roof. The two juxtaposed panels are then assembled one on each side of the clip so
as to be displaced from each other with their upwardly directed joining flanges being
engaged by respective opposed flanges of the retention clip.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a retention clip for standing
seam systems such as shown in US Pat. No. 4,573,300 that will allow free for expansion
and contraction of polycarbonate panels upon the daily variation in temperature of these
long flanged plastic sheets.
It is a further object to provide a retention clip that ensures that the desired gap
between adjacent panels can be maintained at least during construction so as to ensure
accurate fitting and avoid guesswork that is often required using known approaches.
It is yet a further object to provide a retention clip where the gap is not retained
between two spaced apart wall surfaces but is assured by means of a modification to a
single wall surface only thus resulting in a simpler construction.
These objects are realized in accordance with the invention by a retention clip
characterized by claim 1.
BRIEF DESCRIPTION OF THE DRAWINGS
In order to understand the invention and to see how it may be carried out in
practice, embodiments will now be described, by way of non-limiting example only,
with reference to the accompanying drawings, in which:
Fig. l a shows pictorially a pair of juxtaposed panels joined via a prior art twopart
retention clip;
Fig. l b is a detail of the retention clip shown in Fig. la;
Fig. 2 shows a retention clip according to an embodiment of the invention;
Fig. 3 shows a pair of juxtaposed panels joined via a retention clip according to
an embodiment of the invention;
Figs. 4 and 5 show pictorially retention clips according to other embodiments of
the invention; and
Figs. 6a and 6b show front and back views of a retention clip according to
another embodiment of the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
Fig. 2 shows an isometric view of a retention clip 40 according to a first
embodiment of the invention. The general structure of the retention clip 40 is similar to
that disclosed in above-mentioned US Pat. No. 6,164,024 in that it comprises a base
plate 4 1 having a pair of opposing flanges 42, 43 at least one of which 42 is configured
for attaching to a support structure 44 shown in Fig. 3. To this end, the flange 42 may be
provided with apertures 45 constituting attachment means allowing the retention clip 40
to be bolted to the support structure 44 in known manner.
The retention clip 40 has a top plate 46 formed of a pair of opposing flanges 47
and 48 and is joined to the base plate 4 1 via an upright 50 extending between the base
plate 4 1 and the top plate 46. The upright 50 defines opposing first and second surfaces
49 and 49', respectively, that engage opposing first and second ends of a pair of first and
second adjacent panels 5 1 and 52 of a panel system 55 shown in Fig. 3 so as to allow
mutual sliding of the panels relative to the retention clip 40, which is fixed to the
structure 44. The panels 5 1 and 52 have respective upwardly projecting flanges 56, 57
that may be indented and support a sealing cap 58 that serves both to seal the joint
between the two panels and secure them in interlocked engagement.
It will be apparent that, at least in form, the retention clip 40 as so far described
shares much of the structure of the clips described in US Pat. No. 6,164,024 such as Fig.
7 thereof. We shall now explain wherein they differ.
The retention clip 40 according to the invention is characterized by one or more
spacer elements 60 emerging from at least one of the first and second surfaces 49, 49'
that prevent the first end of the first panel 5 1 from abutting the second panel 52 at least
during construction of the panel system 55. The spacer elements 60 may be resilient
fingers or springs and help to reduce friction in the panel system 55 as will be further
described below.
Upon installation, spacer elements 60 dictate a gap between the first panel 5 1
and the first surface 49 of the clip 40, so that the first panel 5 1 is free to expand
thermally in the lateral direction 14 (as shown in Fig. 3) and thus not apply undue
pressure on the first surface 49 of the clip 40 when the temperature of the panel rises.
Consequently there is little or no friction between the clip 40 and the panels 51, 52,
which are now also free to expand longitudinally (i.e. in a direction normal to the paper
in Fig. 3). In this arrangement, the problems of panel distortions and expansion rippling
are greatly improved.
In all embodiments, the retention clip 40 may be bolted to a purlin or rafter
constituting the support structure 44 with bolts 53 through the apertures 45. Typically,
the head of the bolt 53 projects above the support surface 44 so that the panel 52
supported on this side of the retention clip 40 i.e. on the flange 42 is lifted off the
surface of the flange by a distance equal to the height of the bolt head. To compensate
for this and ensure that the complementary panel 51 is level with the panel 52, at least
one spacer 54 is provided on the upper surface of the flange 43. The height of the spacer
54 is the same as that of the bolt head thus ensuring that the lower surfaces of the two
panels are level.
It should be stressed that the present invention is not limited to the structures
illustrated in Figs. 2 and 3. For example, spacer elements 60 may be located in one or
both surfaces 49, 49' of the retention clip 40, have various shapes, oriented vertically,
horizontally or otherwise, as partially illustrated in the examples in Figs. 4 and 5. Thus,
referring to Fig. 4 the retention clip 40 is a unitary construction formed of folded sheet
metal such as stainless steel and spacer elements 60 are partially punched from the first
wall surface 49 of the upright 50 and bent outward to form a pair of resilient fingers.
Fig. 5 shows a two-piece construction also formed of folded sheet metal, such as
stainless steel, wherein an aperture 6 1 is formed in the first wall surface 49, typically by
punching, and a single spacer element 60 in the form of a resilient finger is attached at a
lateral edge to the retention clip 40. This may be done by crimping between the mating
wall surfaces 49, 49' or soldering, welding, gluing etc. The resilient finger is bent
outward to provide the required gap while being compressible upon thermal expansion
of the juxtaposed panels.
It should be noted that in all embodiments the spacer element 60 must be
sufficiently strong to withhold the attachment force applied by the person installing it
and to resist the clamping pressure of the sealing cap 58. Yet it should also be
compressible under the expansion forces applied by the heated panel. It may be elastic
so that it resiliently springs back to its originally uncompressed form upon panel
contraction.
It should also be noted that while in Figs. 4 and 5 the resilient fingers
constituting the spacer elements 60 are oriented in a direction parallel to the base plate
41, they may equally be oriented in a direction normal to the base. In Fig. 5 only a
single resilient finger is attached at its edge to an edge of the aperture. However, it will
be appreciated that a pair of resilient fingers can be attached to opposing edges of the
aperture, each spanning approximately half the length of the aperture. Also, more than
one aperture may be provided each in association with one or more spacing elements.
Likewise, in all embodiments the retention clip 40 may be formed of folded
sheet metal so as to form a unitary construction, to which the spacer elements 60 are
then attached either fixedly or detachably. In some embodiments, such as shown in Fig.
5, the spacer elements 60 are also formed integrally to form a complete assembly of
unitary construction.
Figs. 6a and 6b show front and back views of an alternative retention clip 40
wherein the spacer elements 60 are detachable. To this end, opposite edges of the first
wall surface 49 are provided with cutouts 62 for accommodating a peripheral groove 63
of a respective frangible tubular spacer element 60. During installation, the retention
clip 40 is bolted to the support surface 44 with bolts 54 through the apertures 45 as
shown in Fig. 3. The first panel 5 1 is then mounted with its end abutting the second wall
surface 49' after which the second panel 52 is installed with its end abutting the free
ends of the spacer elements 60. The spacer elements 60 are then broken off leaving a
gap between the second panel 52 and the retention clip 40 which allows for free thermal
expansion and contraction of the panels. The two panels 5 1 and 52 are then secured by
snap-fitting the sealing cap 58 on the upwardly protruding flanges 56, 57, in known
manner.
CLAIMS:
1. A retention clip (40) for use with a panel system (55), said retention clip
comprising:
a base plate (41) having a pair of opposing flanges (42, 43) at least one of which
is configured for attaching to a support structure (44);
a top plate (46) having a pair of opposing flanges (47, 48); and
an upright (50) extending between the base plate and the top plate and defining
opposing first and second surfaces (49, 49') that in use are dimensioned to engage
opposing first and second ends of a pair of first and second adjacent panels (51, 52);
characterized in that:
at least said first surface (49) supports a spacer element (60) that is configured to
prevent mutual abutment of opposing ends of the first and second panels (51, 52) at
least during construction of the panel system.
2. The retention clip (40) according to claim 1, wherein the spacer element (60) is
configured for removal after securing the first panel so as to leave a gap between the
first end of the first panel (51) and the first surface (49).
3. The retention clip (40) according to claim 2, wherein the spacer element (60) is
frangibly attached to the upright (50).
4. The retention clip (40) according to claim 1, wherein the spacer element (60) is
resiliently supported by the first surface (49) of the upright (50) so as to protrude
outwardly from the first surface, thereby defining a gap between the first end of the first
panel and the first surface.
5. The retention clip (40) according to any one of claims 1 to 4, wherein:
the base plate (41) has a pair of opposing flanges (42, 43) at least one of which
(42) is provided with attachment means (45) for attaching to the support structure; and
the respective flanges of the base plate and the top plate extend outwardly in
mutually opposite directions from the upright.
6. The retention clip (40) according to claim 5 wherein:
the attachment means comprises one or more apertures (45) in only a first one
(42) of said flanges of the base plate for accommodating therethrough respective bolts
(53) each having a bolt head; and
a second one (43) of the flanges is provided on an upper surface thereof with at
least one spacer (54) whose height is the same as that of the bolt head thus ensuring that
the lower surfaces of the two panels (51, 52) are level when located on the respective
flanges (42, 43) of the base plate (41).
7. The retention clip (40) according to any one of claims 1 to 6, wherein at least the
base plate (41), the top plate (46) and the upright (50) are formed of a unitary
construction.
8. The retention clip (40) according to any one of claims 1 to 7, wherein the base
plate (41), the top plate (46) and the upright (50) are formed of folded sheet metal.
9. The retention clip (40) according to claim 8, wherein the spacer elements (60)
are partially punched from the first wall surface (49) of the upright (50) and bent
outward to form a pair of resilient fingers.
10. The retention clip (40) according to claim 8, wherein an aperture (61) is formed
in the first wall surface (49) and the spacer element (60) is a resilient finger attached at
an edge thereof to the retention clip (40) at an edge of the aperture.