Note: Descriptions are shown in the official language in which they were submitted.
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CHAIN GUIDE FOR OVERHEAD DOOR OPERATOR
This invention relates to roller-chain driven,
power-operated overhead door operators, and in parti-
cular to a roller-chain guide for 6upporting long runs
of chain in such a door operator.
BACKGROUND OF THE INVENTION
While overhead door openers have taken a
variety of forms, one of the more common types for
moderate to heavy service in opening and closing
horizontally-sectioned folding vehicle doors employs
parallel-rail overhead trackage for a trolley connected
by a suitable link or linkage to the upper section of
the door, and drawn to and fro on the rails by an essen-
tially endless roller chain trained over a drive
sprocket at one end of the track and a return sprocket
at the other.
As each run o~ the chain in such arrangements
is somewhat longer than the height of the door, it is
apparent that as sprocket size is reduced for overall
height reduction in those chain drives whose chain loops
lie in a vertical plane, the catenary sag of the upper
run of the chain can bring it into contact ~ith the
trolley as those members move in opposite directions
during operation, particularly in drive chains of
door-operators for ta}l doors. Not only is such contact
noisy, but the sliding contact of the chain links with
the upper surface of the trolley causes unnecessary wear
on both the chain and the trolley, needlessly increasing
the expense of maintenance.
It is accordingly an object of this invention ~ ~ ;
to provide a chain guide and support for vertically-
oriented chain loops of door-operators which will lift
the upper run of the chain out of contact with the
oppositely moving trolley, and support the chain by its
35 individual roLlers and thus out of chain-link contact ;~
with the trolLey or other relatively moving parts.
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SUMMARY OF THE INVENTION
This invention contemplates the intermediate
support of the otherwise unsupported expanse of chain
between the drive sprocket and the return sprocket at
opposite ends of the chain run. It further contemplates
a lifting guide in the form of a trough having a central
longitudinal ridge upstanding from the floor of the
trough sufficiently to elevate the chain links above the
floor of the trough while the flat top of the ridge
supports the chain in rolling contact with its rollers,
and with running clearance between the ridge track and
the flanXing links of the chain. In this arrangement,
supporting sliding engagement of the roller chain by its
links, and the attendant wear of chain and contacting
part alike, are essentially avoided.
DESCRIPTION OF THE DRAWINGS
The invention is explained in the following
specification in re~erence to the accompanying drawings,
of which:
FIGURE 1 is a diagrammatic side elevation of
the chain loop of a door opener illustrating in somewhat
exaggerated form the ~atenary sag of the upper run of
the chain when unsupported;
FIGURE 2 is a view similar to FIGURE 1,
showing the upper run of the chain supported by the
chain guide of the invention carried atop the trolley of
the operator;
FIGURE 3 is a Vi2W similar to FIGURES I and 2
but showing the chain guide o~ the invention in a fixed
mounting atop a spacer bar which holds the trolley
tracks in parallel ~paced relation;
FIGUXE 4 is a per~pective view, partially
broken away to foreshorten the trackage and chain run,
illustrating the form ~f chain guide atop the trolley;
FIGURE 5 is a view 6imilar to FIGURE 4,
showing the alternate form with cha$n guide atop a rail
spacer;
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FIGURE 6 is a cross-sectional view of the ~orm
of trackage and chain guide shown in FIGURE 4,
FIGURE 7 is a fragmentary enlargem~nt of the
chain-guide portion of FIGURE 6;
FI~URE 8 is a cross slection of the alternate
form of chain-guide mounting of FIGURE 5; and
FIGURE 9 is a fragmentary enlargement of the
chain-guide portion of FI~URE 8.
DESCRIPTION OF PREFERRED EMBODIMENTS
FIGURE 1 illustrates the problem in ~ertical-
loop roller chains employed in door openers, namely,
that the unsupported upper run of the chain 10 may sag
sufficiently to contact either the lower run oP the
chain itself or the trolley 12 which is moved along the
rails by the lower run.
FIGURE 2 illustrates diagrammatically the form
of the chain guide of ~he invention shown in FIGURES 4,
6, and 7, i.e., wherain the chain guid~ 14 is mounted
atop the door-opener trolley 1~, and the upper run of
the chain is engaged and lifted by the chain guide of
the trolley as the latter is moved to and fro along the
trolley track to raise or lower the door. It will be
understood, of course, that the chain 12 i6 motor driven
by chain- or other suitable-drive to the shaft 16 of one
of the sprockets 18 illustrated in FIGURE 4, and that
the trolley 12 has pivotally connected to its underside
a draft link suitably connected to a bracket on the
upper door section to raise the door and to pull the
folding sections thereof away from the door opening as
the trolley is drawn in one direction along its track,
and to lower the door by reversal of the drive motor and
direction of movement of the trolley to push the
connecting link in the closing direction to low~r the
door. These auxiliary parts and their relationships,
being conventional and well understood, are not
illustrated in the drawings.
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Referring ~till to FIGURES 4 and 6, the
endless chain 10 is connected to the trolley 12 by means
of a threaded rod 20 which passes through a longitudinal
groov~ in the trolley, shaped to accept and to confine
the rod. One end 22 of the rod 20 is flattened to fit
between the chain links at one ~nd of the chain and
drilled to be secured thereto by a suitable pin with
fastener to prevent its dislocation. The rod 20 emerges
from the opposite end of the trolley, passing through a
metal bracket 24 which is secured to the trolley by a
nut and locknut on the rod 20, and ~ecured to the
opposite end of the roller chain 10 in the same manner
as the chain is connected to the flattened end 22 of the
roa 20.
The trolley 12 itself, referring to FIGURES 4
and 6, is an extruded aluminum member which fits between
a pair of opposed rails 26, illustrated as angle rails,
which are held in spaced and facing relation to present
horizontal flanges 28 to running grooves 30 formed in
opposite sides of the trolley. The dimension of the
trolley 12 in the direction of the chain run is adequate
to stabilize the trolley on the rails 26 against the
turning moment occasioned by the vertical offset between
the rail-receiving running grooves 30 and the underslung
pivotal connection 32 of the operating link of the door
to the depending saddle flanges 34 of the trolley.
The chain guide 14 itself, which may be
extruded integrally with the trolley or separately
secured thereto in any suitable fashion, is essentially
co-extensive with the trolley 12 in the direction of the
chain 10, and formed on its top to have a longitudinally
extending groove 36, the sidewalls 38 of which are
preferably sloped to narrow the groove at the bottom,
and the bottom wall of which is provided with a central
longitudinal ridge 40 best seen in FIGU~E 7. The depth
of the groove! 36 is 6uch as to accepk the ~ull height of
the chain 10, which is supported by its individual
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rollers 4~ on the flat top of the central longitudinal
ridge 40 at the bottom of the groove.
As shown in FIGURE 7, the height o~ the
central ridge 40 elevates the chain links 44 clear of
the bottom of the groove and out of sliding contact with
the floor and sidewalls of the groo~e.
In terms of dimensions, the height of the
central ridge 40 above the floor of the trough is
greater than half the di~ference between the height of
the chain links and the diameter of the chain rollers.
Its width is also sufficiently less than the length of
the chain rollers to provide running clearance between
the links and the side surfaces of the ridge, and to
accommodate minor misalignment of the guides.
That is to say, the chain 10 is supported on
the central ridge 40 of the groove entirely by its
rollers 42 and simply rolls through the groove with no
frictional sliding contact with the chain guide except
for the confining contact between the inner surfaces of
the chain links 44 and the side surfaces of the central
~upporting ridge 40 which serves as a track for the
rollers of the chain. Contact pressure between these
surfaces, however, is free from the effect of gravity
and does not occasion extensive wear. As the individual
rollers 42 of the chain 10 meet the oncoming end of the
chain guide 14 in the ~orm of FIGURES 4, 6, and 7, each
individual chain roller 42 moves onto the central ridge
40, the opposite ends of which may be beveled slightly
$o smooth the contact of the oncoming chain rollers
therewith.
In the alternative form of chain-guide
mounting of FIGURES 3, 5, 8, and 9, i.e., with one or
more chain guides 14' mounted on rail spacers 46 in lieu
of a single chain guide atop the trolley 12, the chain
guide 14' is ]preferably extruded integrally with the
rail spacer 46, one or more which are secured by screws
48 to the vertical ~langes of the opposed rails 50 and
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formed for a lapping fit with the rails, illustrated as
T-shaped in FIGURE 8. The form of the grooved chain
guide 14' is identical in cross Rection to that of the
form of chain guide 14 carried atop the trolley earlier
described in connection with FIGURES 4, fi, and 7, and
bears the identical relationship to, and provide~ the
same support of, the chain 10' by its individual rollers
as the chain passes through the. chain guide.
In ~oth forms of the invention, the support of
the chain guides 14 and 14' is derived from the trolley
rails 26 and 50 themselves respectively, in the one case
being formed as part of, or as mounted upon, the trolley
12 itself, and in the other case as an integral part of
one or more rail spacers 46, thus lifting the upper run
15 of the chain out of contact with the upper surface of
the trolley passing underneath.
The support of the chain lO by its rollers 42
rather than by the connecting links 44 of khe chain,
protects both the chain and the chain guide from the
wear occasioned by sliding contact with the links of the
chain, and reduces both the wear and the noise here-
tofore experienced from the gravitational sag of the
otherwise unsupported upper run of the endless drive
chain.
The features of the inYention believed new and
patentable are set forth in the appended clai~s.
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