Note: Descriptions are shown in the official language in which they were submitted.
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FAN BLADE IRON ISOLATION
TEgHNICAL FIELD
This invention relates to a fan system for mounting blade
irons and blades, and specifically to systems for isolation of
the blades of a ceiling fan from vibrations of the drive motor.
BACKGRQtIND OF THE INVENTION
Many different types of fans exist today, such as ceiling
fans, table fans, pedestal fans, and fans used in conjunction
with mechanical equipment. Most of these fans include a blade
and a blade mount or blade iron which couples the blade to the
motor.
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Electrically powered ceiling fans typically have a motor
mounted within a stationary housing that is suspended from a
ceiling. Tn operation, the motor rotates an annular array of
individual extensions in the form of blade mounts or blade
irons. Each blade iron is associated with a blade mounted
thereto.
The blades of ceiling fans are usually coupled to the
blade irons by passing mounting screws through holes in the
blade and into threaded holes in the blade iron. The blade
irons are then mounted to the motor.
Ceiling fans are particularly susceptible to the
transmission of motor-induced noises since by reason of their
large area and length, the blades tend to act as resonating or
sound transmitting devices, and thus tend to impart into the
air, as noise, vibrations or the like which the blades receive
from the drive motor. The drive motors themselves, while
relatively quiet by themselves, nevertheless when used to
drive ceiling fan blades can impart objectionable noises to
the surrounding atmosphere through the blades. Thus, a noisy
stator caused for example by slightly loose stator
laminations, which would produce an otherwise relatively
unobjectionable and unnoticeable stator hum, may at times be
transmitted through the motor structure through the blade-
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mounting cage or rotor to the blades themselves and produce an
objectionably loud noise. Similarly, rotor vibrations or
noises and bearing noises may be amplified by the blades and
become objectionable.
Accordingly, it is seen that a need remains for a ceiling
fan system that can restrict the transmission of noise to the
rotating blades. It is to the provision of such therefore
that the present invention is primarily directed.
SUMMARY OF THE INVENTION
In a preferred form of the invention a fan comprises an
electric motor, an annular array of blade irons, and a ceiling
fan blade associated with each blade iron of the annular array
of blade irons. Each blade iron has at least one mounting
hole therein and an elastomeric grommet positioned within the
mounting hole. Each blade iron of the array of blade irons is
coupled to two oppositely disposed other blade irons of the
array of blade irons.
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BRIEF DESCRIPTION OF THE DRAWING
Fig. 1 is a perspective view of a ceiling fan embodying
principles of the invention in a preferred form.
Fig. 2 is a perspective view of a portion of the ceiling
fan of Fig. 1.
DETAILED DESCRIPTION
With reference next to the drawings, there is shown a
ceiling fan 10 having an electric motor 13 connected to a
source of electric power by unshown wires. The motor 13
includes a bottom mounting plate 14 coupled to the rotor so
that it rotates during operation of the motor. The motor
bottom mounting plate 14 has an annular array of threaded
mounting holes 19. The ceiling fan 10 also includes an
annular array of blade irons 16 coupled to the mounting plate
14, each having a blade 17 mounted t2lereto in conventional
fashion.
Each blade iron 16 has a motor mounting flange 21
configured to be coupled with the bottom mounting plate 14 of
the electric motor 13. Each mounting flange 21 has a
depression or recess 23 extending from the bottom surface 24
and inward surface 25, an end tongue section 26, and an end
groove section 27 configured to receive the end tongue section
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26. The end groove section 27 includes an alignment pin 28
and a threaded mounting hole 29. The end tongue section 26
includes an alignment hole 30 configured to receive the groove
section alignment pin 28, and a countersunk hole 31 which is
aligned with mounting hole 29. A threaded mounting screw 32
is passed through tongue section countersunk hole 31 and
threaded into groove section mounting hole 29. As such, each
mounting flange 21 is coupled to its two oppositely disposed
and adjacent mounting flanges 21 with the tongue and groove
sections providing limited movement therebetween. The recess
23 extends from the bottom surface 24 less than the full
thickness of the mounting flange and thus leaves a relatively
thin section 35 of the flange. The recess 23 also includes a
semi-circular inwardly opening aperture or slot 38, which
interrupts the inward surface 25 at a relatively narrow throat
39. The slot 38 is generally aligned with the threaded
mounting hole 19 of the bottom mounting plate 14.
An elastomeric isolation means, in the form of a rubber
grommet 40, is configured to be received substantially within
the recess 23 and particularly supported on the thin sections
35 within the slot 38. The grommets 40 have a generally cubic
shape and are provided with an internal clearance opening 42
which extends axially therethrough. The side walls of the
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grommet 40 are provided with opposed outwardly opening grooves
44, which grooves are proportioned to receive the sections 35
of the mounting flange, at the slots 38, when the grommet is
pressed into place and seated in the recess 23. When the
grommet is thus seated, a portion of the grommet extends below
the section 35 into the recess 23, but the axial thickness of
the grommet 40 is such that the portion which extends into the
recess is fully contained within the recess. Another portion
of the grommet 40 extends above the upper surface of the
mounting flange when the grommet is inserted. The narrow
throat 39 tends to retain the grommet in place.
The opening 42 in the grommet is adapted to receive drive
means in the form of a threaded headed stud 50. The stud 50
is only partially threaded at its outer end 52. The threads
are intended to be received in one of the mounting holes 19 of
the mounting plate 14. The stud 50 extends into the mounting
plate only to a predetermined depth defined by the depth of
the threads 52, and when the same are inserted through the
grommet openings 42, the mounting flanges 21 are suspended
below the mounting plate on the enlarged heads 51 of the studs
50. The grommets 40 preferably are not drawn into direct
contact with the mounting plate 14.
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The grommets 40 provides means together with the stud 50
for suspending the blade irons 16 from the motor mounting
plate 14, thereby eliminating a metal-to-metal contact. The
entire weight of the fan blade 17 and blade irons 16 is
carried on the studs 50 through the resilient coupling defined
by the grommets 40. The enlarged head 51 of the stud is
received adjacent the outer surface of the grommet 40, and
thus the weight of the blade irons and blades normally is
transmitted to the heads fo the studs through the grommets 40.
The connected blade irons with the captured grommets 40 is
free to slide slightly up and down on the threaded studs. The
purpose of the slight axial freedom of movement is to provide
full isolation of the blade irons from the mounting plate 14.
It should be understood that the invention provides an
elastomeric attachment, free of any direct metal-to-metal
contact, between the blade irons 16 and the motor mounting
plate 14. Any vibrations in the motor will tend to be
absorbed in the grommets 40, thereby effectively isolating the
blades 17 from the effects of such direct transmission of
vibration.
It should be understood that the current invention is not
intended to be limited to ceiling fans and may apply equally
to all types of fans. It should also be understood that the
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current invention is not limited to a certain number of blades
or blade irons.
It thus is seen that a ceiling fan is now provided which
isolates motor noises and vibrations in a fan. While this
invention has been described in detail with particular
references to the preferred embodiments thereof, it should be
understood that many modifications, additions and deletions,
in addition to those expressly recited, may be made thereto
without departure from the spirit and scope of the invention
as set forth in the following claims.
